I ordered mine about 30 minutes after it went live, and still no tracking number here.
People have lots of wild theories about when they will ship and why.
All I can say is this, if I don't get my phone until the 21st (or later), AND all of the stores get them on the 21st I'm going to be sincerely irate. The thought of some guy that just heard about the phone walking into a Best Buy and buying an SIII while I wait for UPS to show up at my house between 3 - 5pm irritates me to no end.
I didn't need it last week, I don't need it today or tomorrow either. However if I don't get it by Wednesday and retailers have them on Thursday I'm going to be very disappointed with Sprint and/or Samsung. It renders the whole preorder useless, especially if these retail stores start offering better deals than what we got ordering straight from Sprint (like a 50$ Best Buy gift card).