Good luck. Remember that climbing it is only half way...

http://www.seattletimes.com/seattle-news/father-climber-found-dead-on-mount-rainier-had-gone-to-get-cook-stove/

At least late July.

Check Cascade climbers forum and the climbing rangers blog.

http://mountrainierconditions.blogspot.com/2015/03/disappointment-cleaver-2015.html