Unfortunately, I would not count on the 6 months time frame.......look at Les Mis--the full version has been restricted for several years (although they did release a school version).  I've been told by MTI reps that Hairspray will be available sometime but it all depends on a number of factors such as if a tour will continue etc. I was told a decision may come in October.....   Legally Blonde has a national tour out there that will continue through next year and I could almost guarantee you that you will not see it available for a couple of more years yet (I hope I am wrong).

 

MTI puts their new acquisitions on the website and in the catalogs as soon as they buy the rights to them.

They are often on "restriction" for very long periods of time ... also they can go on restriction after being released for any number of reasons - often a touring company starts up, a revival on Broadway, etc.

I wouldn't plan a season around them until they're announced as available. Even after they become available, they can be a bit of a problem to get rights until they've been around the block a few times by larger regional theatres.