I've gotten most of the pattern testers replies back. I'm working on adjusting sizes for larger and smaller hats. I wanted to share a site I found extremely helpful to figure out sizes. This comes in real handy when you don't have a little one of your own the right size to test model.
Bev's Country Cottage
Bev lists head sizes by age in inches and centimeters, also give approximate height hats should be. If you scroll down on the pages she lists measurements for lots of other stuff too.