C.C.
So your daughter is currently 3? I'd just put this out of your mind for at least another year. Have her do Pre-K in a year, and at the end of that year, see where she is in terms of Kindergarten readiness. There's no reason to get too far out in front of this decision now. Unless something goes incredibly wrong in the next two years, she will be fine going into Kindergarten at 5 (or almost 5, since she has an October birthday).
Honestly, all of the hand-wringing that people go through with regard to starting their kids in K is baffling to me. One of my kids was almost 5 starting K (mid-September birthday), and the other had just turned 4 (mid-June birthday) and both of them have done absolutely fine in their academic careers so far (they're both in middle school now).