Answer: Provide a general college preparation early in high school, and then fill in gaps later!
First, plan your high school courses keeping normal college preparation requirements in mind. This article will help you figure out what "college prep" means. Planning High School Courses. And this article is helpful to learn about science labs: You CAN Teach High School Science Labs!
As your child gets older, you'll begin to look at colleges. If you are looking mostly at prestigious, highly selective schools, look at requirements they have. Think in general terms: in general, those schools like extra testing. If you are looking at local private universities, visit them and ask about their unique requirements.
When your child is a junior the college search begins in earnest. That's when you'll find out what is required by "that" certain college. You will have plenty of time to meet those requirements because you've handled all the general requirements during freshman and sophomore year. You'll be ready for anything they throw at you!