MLS likes to coordinate things at all levels. This year, Jersey Week is February 28th to March 7th, though a few teams have already had official reveals. Seattle Sounders FC will reveal both their primary (the leaked Rave Green with pinstripes) and their secondary kit (which Sounder at Heart is confident is primarily white).
RSL, Chicago, LA, Red Bull, Portland and Seattle do not have locations for their fashion reveal listed at this time.
In 2015 Sounders' three kits will be Rave Green, a white and Pitch Black. Based on historic usage they will wear the greens in 90%+ of MLS matches. Pitch Black is likely to be the choice for the Open Cup and CONCACAF Champions League matches. The alternate whites are likely to be worn in Portland, if the Timbers wear their greens.
Seattle already released their light grey training tops. If you are a size small, you can still get a highly discounted authentic Shale kit through the team store.
MLS will soon consolidate its online sales under one vendor.