I agree fully with (and am in the same boat as) @amortelito. I drew quite a bit (and worked on kinda) a comic in highschool, pretty much took a few years off of drawing for fun in college (I studied architecture so I still drew a lot.. just buildings, instead of characters xD) and only started working on my first "serious" comic after I had been working full time for a year.
In short I would highly recommend you "focus" on academics, for the reasons many listed above. Although they're not strictly required for every job, many of the best require them (and they just generally open a lot of options). Buuuuut going back to the first point, do drawing/comics too! Time management is hard and doesn't really get easier. You just gotta exert some discipline and make it fit.
Now then, some general tips:
- Find a schedule that works for you. There's a reason many hobbyist comic artists only upload a page a week or sporadically. We're busy with our other responsibilities too. Don't stress if you can't match someone else's pace. Find your own~
Do try to get into the habit of drawing every/most days. No matter how much free time you technically have, this is difficult to manage. Especially if you have other hobbies. I know you said a sketch daily thing wasn't working out for you, but the tool i used to help find my balance was inktober 2017. First one I did, and just figuring out how to squeeze drawing into my schedule every day was helpful, for me at least.
- That said, don't be afraid or feel bad about taking breaks! Inktober is the only period I draw legit every day (2018 was intense because it was my first one working and doing my comic at the same time xD 2017 was just work), the rest of the year varies. I do have to draw most days to upkeep my comic schedule, but there are many days where i meet up with friends after work, or on the weekend, or are just lazy and would rather play video games. That's totally cool~ the only time it's not is if drawing is your job xD
- i like this advice for all newbies, but consider starting with a small project or two (or three, or ten) no matter your time situation, hopping into a long multiple chapter story right off the bat is daunting, and comics in general have a big learning curve! Your first pages will definitely be your worst and least efficient, so consider getting those "warm up" pages out of the way in a self contained short story (s)! Write something you can complete in a few months: you'll learn a lot and probably feel good about having a finished project in hand too :>
I think that's about it. Most people manage to do school/work and drawing at the same time (at least at a hobby level), so I believe in your ability to as well! Best of luck!