A big part of that answer is "Do you commute?" Commuting will tear your luggage up in a year. I would say, but the MINIMUM required for now. 2 company shirts and a pair of pants. Most of the company produced stuff is inferior quality to what you can buy elsewhere.
Get a cheap chart case--if your company requires it, and COSTCO luggage, which has a lifetime warranty. After you've been online awhile you'll figure it out. AND if you must have a cool pilot watch, for pete's sake don't buy it from the mall next to the training center!