Cut some hickory staves today and wanted to know how long to dry.Have not made a bow yet but looks like fun and wanted to give it a try.
You could take one and rough it out to near bow dimensions. Leave the handle wide and the nocks an inch wide for now. It will dry faster. Otherwise it takes an inch per year of thickness. Pop off that bark right away or it will cement itself to the back. There's info on my site. Jawge
http://georgeandjoni.home.comcast.net/~georgeandjoni/
Seal the ends and then split the stave so you can seal the back. Funny, I just did the same as you today. I cut some hickory saplings.
Drying wood (http://analogperiphery.blogspot.com/2008/08/drying-and-seasoning-wood.html)
hope that helps.
You can get it to bow dimensions and 5/8" thick and have it dry enough in a couple months or sooner. Leave it in an air conditioned house in a sunny window if possible.