Time is such an issue, isn't it? Writing a novel around family, work, friends, and everything else requires serious commitment. This is true whether we're polishing our best work or pushing through the sh**ty first draft.
Just ask Brad. When we were dating, he and I had this same discussion about balancing creative pursuits with family and jobs that pay the rent.
What? Brad Pitt and I never dated? And he has no idea who I am? The Brad in this picture might even be made of wax?
My point is, this is not a new problem for novelists (or actors, I assume).
Whether I have a lot of time or very little, I try different approaches. Sometimes I find I'm most productive and happiest when I require a certain amount of words per day. That's how I wrote most of the first draft of my last completed novel. Sometimes I work better with a schedule based on time. This spring I was crazy-busy, and x amount of time per day worked best for me. I find time can be saved either way if I work on my manuscript almost every day because the story stays alive in me, and I don't waste time on re-entry.
How are you most productive?