Did they say "if you wait too long you will only get one day of early access"? The point is their tentativeness. Everything is wrapped up in maybes and up tos.
BTW, if they give anyone who pre-ordered in December less than 5 days, the "up to 5 days" would be a lie, since no one who sees it now could possibly get up to 5 days, right? I guess that's what the asterisk is for.