I hate to come home from work every day only to continue working. That's the reason why I try to work on my side projects in the morning. I would wake up early and start working on my side projects. By 9 a.m., I have done with it, no more side projects for that day. In my case, one or two hours before leaving for work and one hour while commuting in the train.
Side projects are more about building a habit
Here's how time usually divided: eight for sleep, eight for full-time job, and eight for others. The last eight is very tight considering that it includes commuting time, dinner with family, playing a game with kids, and exchanging stories with your wife or husband. That's why side projects are more about building a habit than trying to achieve always-moving goals. It is frustrating to always think about goals in very tight time constraints.
Work during weekends and holidays
I work on my side projects every day even during weekends and holidays. I start from 5 a.m. or 6 a.m. I usually have done with the work by the time my kids wake up. Enough work for that day. Time to spend time with family.