Next month, it changes to the pre-registration system which you can actually start now. I've reserved my spots for my boys so that I can go when we are ready without having to wait. Just go to shop.lego.com/minibuild-registration to get started.You will need to bring a picture ID.
June looks to be full of fun. According to the calendar, June 22-28 is when you can get a free Lego Star Wars poster with ANY Star Wars purchase. Even something as small as a key chain.
June 8-12 there will be a dinosaur scavenger hunt. Find all the dinosaurs hidden in the store and you get your passport stamped.