I just don’t see the down side of waiting. If you wait and they are ahead and you decide to accelerate them academically that is fine. If they aren’t ready and they fall behind, it’s tough to catch up if you pushed them early.
In the experiences of when I went to school and my kids having and last still going. Very few times have a I seen a kid who is born august or later be academically, socially, and emotionally (all three together) similar to their class. Usually at least one behind, not all, but more often than not in my experiences.