What age to repatriate for school?

We are living in Trinidad and our son is now 5. My husband has been offered a job back in the States but it is not really a job he wants to do so we were going to take some time off to live on the beach somewhere, until the oil & gas industry comes back to life and there are better jobs for him at his level which I am all for, and there is a small "international" Montessori school there we could send him to temporarily, plus he would be learning a second language (in Brazil where he was born) and get to spend time with his dad and bond more since dad would be around more. And he is already reading, writing and doing simple math so i thought I could supplement temporarily while we are away. We are stressing over the decision though, wondering at what age he really needs to be back in the US for school- we didn't intend on going back until he was quite a bit older and are afraid we will get stuck there and not be free to go abroad again. Thoughts on what ages you should really try to get your child back home for school?