Idk, just whenever you're ready. You should mostly (if not completely) heal from the previous one. That takes a diff amount of time for everybody and for every relationship. BUT, my ex would say 1 month, apparently, and I'm upset about it still

There's no one answer for everybody...there's even no one answer for the same person in different relationships. I imagine it's easier to move on if you were the one who did the dumping, if we're being real you were probably already checked out of the relationship for some time