How long?

How long?   2~ 9 days.

1.  Foreign degree certificate, is not US,  scan the original with transalation.   Better with school registrar # or a letter from department chair.

2.  If one of your previous company is merged, or no longer in business, scan your W-2 from that company.

In short, any background check item, if it takes longer, try to prepare an alternative approach.

Good luck.