If I have a location like Bay of Ice or Golden Tooth Mines out and my opponent reveals Rule by Decree, do I draw my card for revealing a new plot or winning initiative before or after resolving the when revealed of Rule by Decree?

After.

You always resolve all "when revealed" plot effects before doing any other passives or responses to anything that happens in the "reveal plots" framework. (Just like you always settle claim before doing any passives or responses to winning/losing the challenge.)

Thanks!