I have been planning and drawing comics since the near end of 2017.
Manage to save preserves until I publish them on Tapas exactly at May 10th, 2019.
The comic is still ongoing for many years to come.
A second comic based on Sci-Fi is planned this year, planning to publish it will be next year or the year after that.
My current comic, I first came up with the idea around February last year. (Though that's kind of misleading since a lot of the characters who aren't the MC and their character arcs were recycled from older ideas that I've abandoned and transplanted to my current comic. Some of those characters are ... hmm, at least 6 years old according to the file details of my earliest drawing of them :o)
As for my future comic which I'm still planning, the earliest drawings of related characters I can find were from March 2015 sooo at least 7 years and counting XD
It's hard to say for me! I posted standalone photographs of it since 2020 on my twitter, then I redid them a few months ago (now I have better equipment!) and put them into a webtoon format not too long ago!
So either 2020 or 3-4 months ago! :o
I've started my ninja comics in February 2013, although current "True Face" (that's a direct continuation) series started in August 2015. I wouldn't say that it was 9 full years of working on it as I had a few longer breaks inbetween. Because of that, it's fun to see how the art style changes between the chapters 
For The Commune:
Created the characters just for fun in 2019
Wrote the story from late 2020- 2021
Started making pages in November 2021 - I first published online at the beginning of this year!
So I've been updating on tapas for about 5 months, but I've been working on the comic as a whole for almost 2 years! I just tend to have a lot of prep work set out for myself to set myself up for success 
For my current series, Frostpeak West, I started planning it last year and posted some concept art around June. Tho I didn’t post the first chapter until September.
However, these characters and plot have sort of been floating around in my head since 2005. I have made changes over the years but I was never found a good way to start the story. I think something that helped me to get it to work was being willing to make huge changes to some of the characters. I think there were issues I was too stubborn to change thus my old scripts were sort of messy as a result.
Around 7-8 years.
Characters were all created around 2011-2012, but the first draft for the story only came to life in late 2014/early 2015. Started to post on Tumblr using game assets in February 2015. In 2017, I began to draw what would eventually become the first page of the comic, but since I couldn't figure out how I wanted to color the damn thing, I set the whole project aside until summer 2020, which is when I finally decided to post it as a comic with actual drawings.
I suppose it depends on when you start counting. If we go by when the MCs were first created, Adi goes back to some writing I did with my then-friend-now-husband, back in 2012. Koreal, one of his old DnD characters, goes back even further.
We continued to write stories with these characters for most of a decade, off and on, but the idea to finally make their story into a comic didn't really occur to me until 2019. At that point, I had tried (and failed) to script several other ideas, and was at a loss and sort of desperate. And then I thought... 'why don't I just use this thing my husband and I have been writing for most of the time we've known each other??? It's not like we don't have enough material to pull from!'
So I started writing the script for chapter 1 in 2019, spent about nine or ten months doing that, and started drawing the prologue in October of 2020. I was afraid to post before I knew I had enough momentum behind me, so I built a buffer of 30 pages before I finally started posting in April 2021.
I was really dumb and lacked the self confidence for a long time, so I never started mine till last year.
The story's conception was back in 2009 when I was a very young teen. I'm happy to say that the story's development over that time has made it much better and stronger as a story, and now I can just focus on drawing it.
So I guess technically 13 years? But truly, just 1! 
I've been working on my romance comic for 8 months now! 
Honestly, I didn't expect it that I've been working nonstop for 8 months haha.
Well, some are not my comics buuuut
Drawing
For Scarlet Society -> Since November 13th, 2018 (Webtoon Canvas1 - Tapas Community)
For Love Quotes -> Since December 30th, 2021 (Webtoon Canvas - Tapas Community)
For 
Solomon's Time -> Since April 30th, 2020 to June 3th, 2020 (Ko-Fi Shop)
For Yandere City -> Since December 30th, 2021 (Series TBA)
For Giri -> Since April 17th, 2022 and still on the making (Webtoon "Call to Action")
Like, submitting it here, 1 year and 6 months.
Drawing it, maybe add 2 more months.
Thinking it, and scripting, etc. Let's add 3 more months.
And to be honest, I kind of rushed the project, because I wanted to draw something soon and easy as a first project. Maybe next one will be more thought.
Writing the first draft of the script for a volume of 3 chapters around 25-30 pages each took me... not that long, actually. It was last September and I was on vacation, so I wrote really quickly in the evenings and got it done in about a week. That first draft, of course, changed quite a bit since then - but the first chapter in total took us around 6 months to do, give or take a week.
The idea for the setting struck me in the middle of the night sometime during December 2020 when I was recovering from COVID, and I've been trying to bring it to life ever since. The main characters for the comic started out as really distant background characters for a completely different plotline, but our artist drew them so appealing that they demanded a plot of their own.
Like seriously working on it, for about 2½ years, but I did do the 10 first pages already in 2016, ad concept and ideas for the character in 2014ish but I got into some major irl issues and had no motivation to keep drawing until 2020 again and just kept going from those first pages, so theyre a bit old compared to after I started working on it again but they still do the job haha 
But yeh, I didnt seriously commit to the comic itself until 2020
but the idea of it have been slowly progressed in my head since 2014
For MagicalMashup!2 Conceptually since 2008. The protags were created to fill a niche interest I wanted to see more of and I'd post illustrations of them with short blerbs about them on ye old DeviantArt.
I didn't get the kick in the butt to go full steam till around 2018 where a friend was just like "Lady. Just. Do. It." And I was like... "I think I WILL gal, no, I totally will." Then I took all the scattered notes, illustrations, cute moments, and Ideas and started to combine them into a long form story.
Better late than never haha 
For me, it was about 1 year of planning/writing/concept art + 6 months of drawing the pages so far.
Been turning out pages too slowly, but that's why I'm making a buffer and haven't released any pages yet.
I've been working on the one I'm drawing at the moment for around six months. About 2-ish months of planning and then 4 months of drawing.
The idea came to me pretty spontaneously near the end of 2021 and since I didn't want to burn myself out starting a longer story that I probably wouldn't be able to finish, I decided to stick with it.
