I have also taken many online classes - probably more than 1/2 my pre-req's have been totally online or hybrid online ones, with only 2 or 3 real-life classroom meetings (at the CC I'm registered through).
When I first started with online classes, I told my 4 kids and husband that this was MY time not to be disturbed, especially when I had an English Lit class that we had to attend online in a chat room 1x/week. Other than that, I do my online work when my kids are at school. I do a lot on the weekends and at night also, but I make it clear that I am studying, and can only be disturbed if there is a broken bone or serious blood spillage! :chuckle Otherwise, go to Daddy! I'm not cooking, cleaning or driving you anywhere until XX o'clock.
Be firm with it though. Study as far away from noise and chatter as possible. I have my 'puter in my bedroom, so I shut the door and turn on some "white noise" like the a/c or fan to drown out any kiddie-bickering.
Some of my online classes have let me work ahead, and I've finished them WAY early (like Medical Terminology
I finished in 5 weeks, compared to a 16-wk course), but some you have to follow the guideline in the syllabus. Just be sure not to fall behind. I fell behind a little in my online Math for Allied Health class when my mother died last fall, and it took my a while to catch up, especially since math is a weak point with me.
I do understand your wanting your own time though. I took a "regular" Human Bio course this spring, every Wed. night, and loved the "me" time. Even just the 45min drive up and back, where I could relax and listen to my music on the radio. It was fun!