i wanted to know, is there a way to know who claimed the first promo? because i claimed shadow vicitini 1 minute after it was launched. and i got an additional message which was like you were one of our first customers and got a rare candy, and since barely 1 minute had passed, i think i was the first one. damn, i forgot to take screenshot,auuu. back to question, is there a way to know that i was the first one?

Yes, there is actually an way.
Go to Pokemon Rankings, view the profile of everyone's ShadowVictini, and each shadowvictini has a unique ID.
So see which one has a smaller ID number and that one is the first one created.