homeschooling, when to start?

Well, I am trying to start some type of routine with my 4 and 2 year olds, and it seems that everyday there is something to break the cycle, now it is the fact that they have colds and sleep till 11. They both catch on very well, even though it seems that my 2 year old daughter is a fast learner and it sometie frustrates my 4 year old. She will be 3 in May if that make any difference, but they are both on the same level. Should I keep teaching them the same things or seperate their lessons, advice welcomed!