Everyone should probably calm down. The Galaxy S10 5G wasn't available on day one either. Neither was the 3G version of the Gear S2.
I was in my local AT&T store on Sunday & they had already setup the display for the GWA2 but they didn't have the signage yet. They weren't sure when they'd get the actual watch but they wouldn't be setting up the display if they weren't going to sell it.
If you go to the product page on Samsung's website, the LTE version is finally listed for sale with an estimated ship date of Oct 25-Nov 1 depending on the color. Not sure the reason for a delay, but it's nice to finally see a timeframe. I ordered from Best Buy two weeks ago before they listed it as Sold Out, hopefully their shipping ETA is similar to Samsung.