Creek SMB usually will spawn in/around June- quite a bit later than the major reservoirs. Of course this is dependent upon the water levels and conditions. I've read elsewhere that they prefer 55-65 degree water for spawning.
Last night was the May full moon which usually marks the first emergence of the crayfish for the year. Creek smallies will begin feeding more- fattening up for a late May/June Spawn. Unfortunately, here in the Louisville area, we are pretty flooded out. Floyd's Fork is blasting, Harrods is way up, and the Elkhorn is flowing at 2820 cfs.
Peter posted a really good, very relatable, article on this year's creek SMB fishing forecast from Lee McClellen of the KDFWR.