Size for baby hat?

OK so I am fairly new knitting. I know how to knit, purl, cast on, bind off. I get the concept of increase and decrease but never done it, and can read simple patterns but complex ones make my eyes glaze over in wonderment. SO I am having a hard time trying to figure out how to knit a simple baby hat. I have some ideas, gonna try knitting in the round and doing some decreasing at the top I am just not sure how large to make it. My daughter had a HUGE head when she was born and the hat they gave her in the hospital wouldn’t stay on her head so I figured I would make one for this baby girl due at the end of September.
Does anyone have suggestions on what size I should make a baby hat for a large headed baby?
thanks!

Babies do have large heads for there size normally and that size can vary. Here’s a basic infant hat pattern.


Head sizes and patterns-
http://www.bevscountrycottage.com/size-chart.html

Simple hat calculator- this may come in handy for you at some point.
http://www.earthguild.com/products/knitcroc/marypat/hatcalc.htm

This head size chart might help; you might go for 15" around. Though these are actual measurements and a hat should be a little less than the head measures.