I had a ‘coding job’ over the summer, and on a typical day my schedule would involve working on my personal project from around 6-8am, leaving for work at around 8:30am, working at work till 5pm (whilst working on my personal project on paper whenever the workload was particularly light, and also during lunch breaks), then after dinner spending a couple of hours reading lecture notes for the next year at uni, and finally spending up to a couple more hours working on my personal project before messing around a bit (e.g. watching a movie or TV show) and eventually getting my 6 hours of sleep.
Over the weekends I’d spend up to a good 8 hours each day on my personal project along side reading more lecture notes.
It only all worked because of a combination of things:
I enjoyed the work I did at work, and the workload was often light and paced at whatever speed I was comfortable with
I enjoyed the work I was doing for my personal project (and I still do)
I was alright with sleeping for as little as 6 hours per day for four nights straight
I enjoyed reading the lecture notes at the pace and depth I was going at
Most importantly my 9-5 workload was ‘light’
When you’ve got a full-time job, and particularly a tiresome one, you’re more likely going to want to reduce the personal project workload to 2-4 hours (including my lecture notes, was doing 6), and try to make use of the possibility of working before work (my opinionated reasoning being that the personal project work is likely to be so little of a drag that it doesn’t affect your day job).