The first lottery date is May 28th. Before that it is still regulated, but first click, first served. Plan on running Marsh Creek for the MFS on the 19th would be my humble recommendation. You will still need all the permit required stuff: pooper, firepan, strainer, ect, ect, ect.
The J/B is, as Im sure you know, a very small window season. I have been wanting to run it for the last 2 years but have not gotten the days off when it has been above 1k and below 4k. If your going to run the Bruneau, run the Jarbidge, the put in for the Bruneau, is....how do you say.........SHITTY!
Someone else will be able chime in a little more on Marsh as I have never run it.