I'm not very good at explaining, but my question is a follow up to this:
So like, I have multiple 3DS's, would the timer reset if I swapped the DS i'm playing in or what?
When entering the Nameless Cavern, The clock is automatically recorded onto the cartridge, so if the cartridge time doesn't match up with the 3ds time, the game will lock the player out 24 hours. Since the Time on the 3ds will not match the time on the cartridge, the cartridge will detect a calendar change and lock out, so you will have to wait. Sorry :(