One of the best things about homeschooling is that you can set your own schedual. This means you can let your kids get the sleep they need. Be it they were up to late because of a parent working late or even just a full day, they can sleep in and catch back up. Kids and teens need 10-12 hours of sleep a night!
So don't feel bad that you are not up and starting school at 8am like traditional school. Happy rested kids concentrate better and have a better attitude towards learning.
I'll be honest, sometimes we have started school just before dinner and finished after dinner. My kids have always done better if I let them get their energy out during the day.