I'm considering cancelling my current Bumbus Queen quest, how long do I have to wait for another if I do cancel it?

You get the quest from an RE (it tells you that a group of Bumbii have summoned you to the Blue Building, or something like that), so you'll have to wait until you get the RE again. But it only changes one of your pets into a Bumbus, and you can create one for free whenever you like, unless you have a specific pet that you want to change.

you don't even have to cancel it... the Bumbii keep coming to me ("get to the queen asap") but I've accepted the quest like one year ago and there is no time limit, too. waiting for the release of an angelic bumbus -_-