I dont know about JBLM, but I have fished a lot of lakes in the King, Pierce, Thurson area, smaller ponds will have them hitting the beds already, larger waters more towards the end of month-April and May.
Good pre-spawn activity, if you are fishing from shore and walk up to water and you might see some wakes from them hanging tight to shoreline, I know a kid who "poke-poles" into some thick shoreline bushes and gets quite a few.... First time I saw him do it I thought he was after frogs, until he hooked a 5#er
