Waited with oldest son whose birthday is in September. Our state’s cut-off is October 1st, and so he barely made that. He was in PS until 4th grade. Didn’t wait with next son whose birthday is in July and regret it to this day. All of the boys in our area are held until age 6, so DS is a year younger than almost all boys in his grade even at church and even among other homeschoolers. Everyone here waits. Our state also doesn’t require they are registered until age 6 for K.
With little DS, who turned 7 this past June, he is in 1st grade and yes, was 6 when he started K last year. Same with DD, 6, who will be 7 in October and is in 1st. By the rules though, she just missed the cut-off. Still we could have started her since she is homeschooled, but we waited until last year for K, when she was almost 6. So this year, 1st and she is almost 7.
I say wait though if you are homeschooling, you can certainly go ahead with learning. But for church classes and such, I would wait if most others do.