Your goal should be to put away as much as you can each month as soon as your child is born. If you didn't start right away, it is still early enough to start saving for college with a long-term investment perspective. However, make sure you are funding your tax-advantaged retirement plans first.
IMPORTANT NOTE: If you think that ultimately you will be applying for financial aid, it is best to invest the money in an account in your name. See the section Landing Financial Aid to help you decide how much you should invest.