as said here : Q: When I'll be able to invite someone via promo-code? Will that someone be able to start a week earlier like me through pre-order? A: Promo code also grants early access, so you will be able to start together with your friend. You will be able to activate the code a few days before the early access starts. I was wondering anyone know's where can we activate the code as they said we could few days before the access starts?