I'm still in the process of setting up a buffer for my comic but I've been drawing a page a week regularly for about a month and a half while working fulltime. I tried the "draw after work" approach and I was seeing very little progress. The fatigue I got after work stopped me from thinking clearly and on the days I didn't lay down for the rest of the night in my bed I would be at my desk just screwing around online instead with the art program open on a separate monitor. So I just decided to go to bed as soon as I get in, wake up, freshen up, and start drawing in the beginning of the day when I'm more focused, rested and my thoughts are clear. I manage to get 2-5hrs of work done this way before going to work.
Everyone's different. My advice is to find what works for you. If your fatigue is preventing you from moving forward, figure out what would best fight that, whether it be a complete change in schedule, cutting out certain unnecessary activities on workdays to sleep more, etc.
Also get better at scheduling.
I don't think anyone who works a fulltime job and regularly works on their comic can be bad at scheduling, end convo. There's no trick or special way around it. You're either bad at scheduling, won't change that, and will therefore make little to no progress in this area or you get better at scheduling and are able to balance both of these tasks consistently.