I had my first at 28 and my last at 37. There are two “sets” – each born 15 months apart, but 6 six years in between. I really let my little ones play and enjoy each other for several years – after all play is their work.
Doing school is not that hard since the kids already read and are capable of following a list themselves with occasional help from me. The family subjects can be tricky sometimes, but you can get audiobooks for a lot of the spines and other books, which allows me to work with the littles while still maintaining a schedule. It is possible.
This year I started a formal pre-school with the two younger (only for about 45 minutes total) but I had planned to add them into some of the family oriented things. It wasn’t working very well since they haven’t been trained to all that “stuff” yet, 😉 so I changed it to more of a focus on getting the older kids’ family subjects first and while they finish up with their individual lists, I will do the much more engaging and “fun” stuff with the littles. Basically, whenever the olders are working on their individual stuff, I work with the littles, whether it is morning or afternoon depends on the day, etc. For our preschool subjects I am using the SCM early years list and the Before Five in a Row books as literature, reading some books about America for history, reading some science books, Math U See Primer (although we are mostly working on number recognition and value still), we love the Letter of the Week alphabet activities, and they do nature walks and study with the big girls. It is fun, but I do not stress about getting it all done every day. They are still young and so I go with the flow. =)
I say that if it is what the Lord is leading you to do, go for it. He will never leave you without a way to accomplish what you are called to do! It’s all good! =)