If they're sealed in mylar, it won't benefit you any further to seal them in a food saver bag. It sounds like they aren't nitrogen flushed. Unless the LHBS threw in an oxygen absorber, figure on about four to six months. If they were nitrogen flushed or do have an oxygen absorber, a year or two or more if frozen.
Beer so good, it's frightening.
2014: Seven Heavens Series One: Vilon, Mystic Melomel, Skeeter Pee.