Get organized. Organize the kids' school books by child and age level on a book shelf or in a cabinet that is easily-accessible to you and your child. Organize your extra supplies you will need for each day. Buy plastic containers and label them for the contents of the container. Organize your work area. Have things in order.
Buy the supplies ahead of time. Home schoolers are at more of a disadvantage than public or private schooled children in that the home schooled family doesn't have a classroom next door to run to and ask to borrow extra supplies. Either you have the supplies and you accomplish the lesson plan for the day or you improvise which takes extra time. Look over the lesson plan and find the supplies before the lesson is assigned. Better yet, buy curriculum that uses "everyday" items.
Determine a schedule that works for your family. Try working early before the kids are awake or during the afternoon "reading" hours. Teaching your child is priority number one. If work gets done last and late, plan for a long night. You have a legal obligation to school the children. Kids have a limited attention span, so take advantage of the times when they are most alert and receptive. School for an hour and then send them off to play while you get some work done.
Hire a mother's helper. The good thing about home schooled teens is that they are often available during school hours. Hire a mother's helper to come in a few hours of the day to take the children outside or somewhere safe to play. Let the kids have fun with the mother's helper and burn some energy before you get back to school work with them.
Farm out certain school subjects. It is okay to have someone else teach your child a subject or two. Think of it as socialization, something that home schoolers are often questioned about depriving their children of. Switch off with other parents and give yourself some time off from homeschooling to work. Be flexible and don't get overwhelmed by it all. There are people and resources to help. You are not the only working parent who is trying to home school.