The way it's been done in the tags I've been in before, it's 24 hours from the time you've been tagged (not from the time you see it). And we'll do it that way here too. If you don't see it because of time zone differences, it's probably because you were sleeping, and that still means you have the whole day after that.

But if you're tagged and discover it late and end up being all panicked by it because you don't have time that day, just pass the tag on! It's not the end of the world. Also, no one will be upset if you post something a little bit late. The goal is to have fun, after all. : )

Or you could make something ahead of time if you want. Personally, I have a back-up idea, but I'm waiting until I get my tag to see if the prompt sparks something. If not, I can always go with my back-up plan.