How long will it take for my brand new domain to start resolving?

Max. time for a brand new domain to become accessible worldwide:
48 hours.

New registrations can take a while to propagate out through DNS, although usually most DNS servers will resolve the new domain within a few hours. Porkbun informs the appropriate registry of your new domain immediately, but it can take some time before the registry makes that information public. Even then, it can take a while longer for some DNS servers to pick it up. This may be why your recently-purchased domain might not receive web requests or emails for up to 48 hours following registration.