Sephora allows you to pick up the b day gift 2 weeks before or after your birthday (you can get it online or in stores). I don't think someone else can pick it up for you because everybody would be doing it.
Sportygirly is right, you have two weeks before and after your birthday to redeem your gift and you can either pick it up in store, or include it with your online order placed within that time frame. Unfortunately you do need to be the one to pick up your gift rather than a friend or family member. Thanks!