Hi Chris
I have yet to see a female A. percula that has reached that 4"+ range that is not at least 5-10 years old.
There is also a BIG wild card here. Clownfish change size based on social interaction. Frankly at this point I am ready to take back "A single clownfish kept by it's self will become female". There is a lot more going on here that we can see with a few observations.
I will be posting in the next couple of months on such things in depth, but since this is such a complex subject, you are going to have to hang in there, lots and lots to put together.