One thing I took into consideration is the developmental leap when they transition to high school. I have four boys and three have their birthday after the cut off anyway so they were five turning six the year they started. My youngest is an April bub. I will most likely send him the year he turns six. But will also see how he is in himself when the time comes. But for me, its the early high school years that I think are the ones to look at. There is a big developmental gap between that twelve months when. You get to that teenage bracket. I would much prefer my boys be older, then younger.