Whaaat... Best Buy doesn't even sell Macs as far as I know. At least, not in their retail stores. And if they did receive them on the 19th, people would freakin' know by now.
The second AI post sounds a lot more promising, but would the retailer really tell him that? I don't think retailers even know about product updates until the same time as the public knows. Again, the news would leak to the public.
Best buy does sell macs in stores. They have a pilot going right now with full apple sections. Also any Best Buy for Business location carries the MacBook Pro. There are no SKU's in the system.
Second is most definitely not true as well. When I worked applecare we did not know about new products until day of anouncement, they definitely wouldnt tell a 3rd party reseller.
Only insight I had was my CTO replacement being delayed a week until tomorrow but even that is a long shot.