Got an invite around lunchtime today in uk and put a preorder in for Mario kart bundle, GameCube controller, sad card and pro controller, honestly I was pretty pissed this morning when I saw that the site had been updated and you needed to be invited just to preorder a GameCube controller, I tried my email address in the validation but wasn't having it, went through every Nintendo online setting I could find and also the account pages of my.nintendo.com and every condition necessary I had set correctly and had been that way since NSO launched and consistently bought several switches off Nintendo uk official store alongside various preorder bundles of games across the years
Glad I got an invite in the end, it was very clear that it was only valid for the day it was sent (today) so if anyone misses that email today and sees it tomorrow then that invite opportunity is gone, bit harsh they don't even allow 24hours, would make a comment about Nintendo Germany perhaps being responsible for the strictness, but I think it's a WW thing, so be prepared to keep checking ur emails for invites