What i can tell you is that many people i know got it at 1050 exact, somebody else at 1120-1150, and i know a guy that got it at 1250, those are sure infos. I c*so tell you, not sure if is actually linked to it or not, but imho it is, that the people that got it at 1050 (i am one of them) were all at only 23-25 fragments of edo hashirama when they got it, while the guy that got it at 1250 was at 29 fragments when was at his 1050th roll.

Then my supposition finds another confirmation with you.

Your kurama was an early rng lucky pull, you simply had the luck to hit that 1/3030 chance you have to pull a super rare on any roll and in your case happened at your 930th roll (it's the same, exact mechanics of common rares with. 1.5% chance to be pulled).

So your case is not at all the same as the case of who gets the super rare because hits the hidden counter and beware that since you got your super rare out of a lucky pull then your nexr super rare may be a dupe, differently from who gets them by hitting the hidden counter.

Unless you gain more than 300 seals per month you should simply skip altogether this rebate and just use 300 seals per time when the other rebate is up.