kids don't start school til they're 5 anyway.
the gov is pushing for kindergarten to be all day, but there are places that still do half day, but these are being phased out. atm, we'd have to pay extra for full day not half, but that is also disappearing.
each state has its own 'cut off' date for the age of kids. in MI, they should have turned 5 by sep 1 to start school that year.
however, where we are, there's the option to hold them back if their birthday is between sep1 and sometime in nov. OR they can start early, OR they can go to 'young 5s' for a year, then start K the year after, but it has to be full days.
so, here, they are v flexible, and you can choose depending on how you think your child will cope.
where you live decides which school your kids go to - so each time you look at a house, find out which school it goes to (if you buy, it's listed on the realtor's details), and visit that school to see what you think.
homeschooling is 'allowed' here, but again, varies on the state. in MI they do check up on progress, but a lot of people do it. the libraries allow people to take out up to 100 books at a time in order to help parents with this.
dd had already done a year & a bit at school when we moved here, and we were living in a one bed apartment, so i got her into school quickly. we had to have some paperwork to prove where we were moving to, before a school could take her. so she had to wait 3 weeks to start school, as it took us that long to choose a house to buy. some areas might insist that you were in your house before taking the child.
i found schools v good at answering questions i sent by email, and very open to having us visit & look around. also, v flexible in when dd started, half or full day etc.
we're lucky - public schools here are lovely. teachers have actually just taken a voluntary pay cut to stop redundancies, and class sizes are about 20. classes also much better equipped than one i've seen in the uk. BUT it varies hugely by area/state etc, so ask first.