I sent my application in a Priority Mail envelope with a self-addressed PM envelope inside. I received my passport back in a week and half, and my licence a few days later, so roughly it took me about 2 weeks. I believe on the application it states to not send them your passport if you need it within a month. (In other words, don't apply until you come back.) I wouldn't want to scare you, but there are some who have had their items lost in the post, so I wouldn't take the chance.