The truly prolific creative people I know do that work at non-traditional times if they have a full time job. Practicing music late at night, painting at 6am, etc. Even scheduling their creative work during low points in their work day.
I am also not good at this, so take this advice as an observation rather than a personal experience.
This is an exercise in "managing your energy, not your time".
For me the first several hours of the day are my most productive/creative, so I carve out at least a couple of those for my personal projects. Lately that's meant getting up early (5:30-ish) and prioritizing my own work ahead of my employer's.
I have found this to be effective, the problem for me is getting into the routine. When it worked, I got up earlier in the morning and was able to devote 1-2 hours to personal projects, 3-4 mornings per week.
At some point, the habit gets interrupted and it's been tough for me to get back into it.
I have 3 kids and get up at 4:30am every day to work on my own stuff. From 7am they're awake so I spend time getting them ready for school, etc. Then I go to work. Over the years I've found that getting this going consistently is the key. Even if you only get one good hour in each morning it builds up to quite a lot of satisfying work very quickly.
It did take a few years to become consistent though.
Usually 9-9:30 pm. Sometimes I'm out or doing something so end up going to bed later after which I'll still get up at the same time the following morning. This makes me more tired so I'll go to bed way earlier on the following night.
The truly prolific creative people I know do that work at non-traditional times if they have a full time job. Practicing music late at night, painting at 6am, etc. Even scheduling their creative work during low points in their work day.
I am also not good at this, so take this advice as an observation rather than a personal experience.