I've totally been there! When I was in middle and high school I used to draw a ton but then I kind of slowed down upon entering university and almost stopped completely halfway through upon entering my architecture design program (would be doing technical drawings and poster layouts all the time all week for school work so I wouldn't feel like doing other drawings in my free time lol).
Upon graduation I decided that I wanted to get back into drawing and comics again... but then after getting a part time job the following holiday season my motivation plummeted again.
After that was over I sought out a full time job, found one, and still didn't really start drawing a whole lot. Same situation as you: adjusting to the new schedule and hours left me drained afterwards (8 hour work day, 2ish hour commute) and I was out of practice so... that was that.
After several months at the new job when I was finally getting used to the new routine I finally decided to take the dive into trying comics again, and the thing that helped was forcing myself to do Inktober that year. Drawing daily like that, even if it was just a quick doodle some days, or like working on the same picture for 2 or 3 days was what I needed to develop a drawing habit again. Like I would get home from work, get or make dinner, bust out my inktober doodle for the day, and then relax with videogames or whatever else. Some days I would hang out with friends or go to a concert or whatever, and so I'd just do something really minimal when I got home later that night. Either way the point was just picking up the pen each night and getting something made.
This sort of habit translates directly into the sort of discipline you need to carve out time to work on a comic while also living life and doing other things lol. The point is even if you just work on it for like a half hour 2 or 3 days a week after work you can make the forward progress you need to make a comic in a timely fashion~
With the long anecdote out of the way, some other tips for when you get into it:
when setting your schedule take it slow at first and be realistic with your expectations. It can be tempting to try and bust out 2 or 3 pages a week but I've found, for me at least, that requires drawing for like 2 hours each night after work as well as a loooong period of time on one of the weekend days. I'm much more comfortable drawing 1 page a week which allows me a lot of wiggle room. Thus I don't promise my readers more than that.
Be kind to yourself. Once you get into a rhythm and have a steady upload schedule going it feels really good... until a busy week comes up or you get sick or whatever and you face the choice of either staying up way too late to finish a page or missing your planned update. Always know that your well being comes first and don't be afraid to take a break or skip an update when you need to. Let your readers know, of course, but this shouldn't take priority over more important things xD
BUFFER BUFFER BUFFER!!! Unless you don't care about maintaining a consistent schedule (which is perfectly fine too!) please invest in a sizable buffer before you begin to upload lol. I started my comic with only like 3 weeks worth of buffer and ran out really quickly... like when I first started out I was drawing 2 pages a week and posting 1, so I was actually building buffer as I went. But when Holiday 2018 rolled around I took an extended break from my comic and lost all of my buffer by like February of this year and have been going with none since then... not fun! Another option to consider is completing a whole "chunk" before beginning to upload, whether that chunk be a whole short story, or a full chapter of a longer story, or whatever. Finish it up, start posting it while you begin working on the next "chunk", and then wait until that next chunk is finished to begin posting and so on. This is the strategy that I'm going to be trying out next- I'm not going to begin posting Season 2 of my comic until it's either all the way or perhaps 80% complete. That way I can work on it around my schedule without the stress of looming deadlines.
I offer this advice to all newer comic artists regardless of schedule, but consider starting small. One thing that can be really frustrating is a story being so long that it takes a considerable chunk of real life time to progress or get to the good parts. This goes doubly when you have a hefty schedule that doesn't allow a lot of time to work on your comic lol. I actually omitted this from the story above, but after that Inktober that I used to get into a drawing habit and before my current comic on Tapas I actually tried rebooting a series that I had been working on since Middle school, which was a long form series inspired by shows that I was watching in that time frame like Naruto. I dropped it on page 8 because I looked at the rate that I was drawing (1 page per week) and then looked ahead to see roughly when the first cool action scene would be in this fantasy action comic and realized it would be like... a full year out lmao. That wasn't going to hold my interest and probably be boring for my readers as well, so I dropped it like it was hot and decided to write a short story from scratch instead. I'm just about to wrap that up in a few weeks actually on or around page 70 and like... it feels totally awesome and like a morale boost to have seen a project all the way through to the end! If I was still working on that other comic that was way too long for my drawing speed and free time, I dunno if I'd have been able to see it through to the "good part" lol.
Anyways those are my thoughts and experiences on the matter~ It's not an easy feat but once you force yourself into a drawing rhythm you can carry that momentum forward and make something cool