My Toys R Us in San Diego confirmed with me over the phone that they're opening early on 8/18 for Disney Infinity at 8am. May want to check your local Toys R Us to see if they're doing the same.
(I think on some thread here someone posted about Toys R Us possibly opening at 9am, but I couldn't find that thread because "toys" "r" "us" and "launch" are all too common to search for =P)
My launch strategy:
8am Target for the Cars and Lone Ranger sets
8:30am Toys R Us for the exclusive Power Discs (if not earlier)
9am GameStop to pick up my Starter Pack preorder and mini-mag