Pre-orders definitely work. I finally stumbled across the new Pokemon games releasing in November (Sun and Moon) and remembered that my daughter wanted those. I pre-ordered one and got the promo code instantly in the email, and she will do the other for her promo code.

Also note that accessories and peripherals like headsets, keyboard or mouse, and video cards are included in the promotion, as long as they are sold by Amazon.com. Do check for the proper promotional text on each product page to be sure it's included.