Pot call wood?

[Goblen]

I'm cutting down a walnut from the river on one of the properties I hunt. Plan to have someone else do the lathe work. I have a couple of questions. Was planning to cut into blanks for 3.5 inch pot calls.
1. What size blank to get cut (green wood/ shrinkage) for 3.5 inch pot? (4.5x4.5x1)
2. Cut into blanks or leave as a whole board and cut after moisture content is correct?

[outdoors]

Should leave as a hole board for shrinkage and cracking

[mastevt]

Should leave as a hole board for shrinkage and cracking

This!  I'd mill to 1.5in thick.  Seal the ends with anchor seal or some old latex paint.  Stack it in a cool dry place, and put an electric fan on low on it.  Takes a couple months, but it does dry pretty good.  Get a moisture meter and write on the boards the MC.