For Donaire, there's enough time for practice and actually, he is practicing the whole year-round. Donaire fights this year and just a few months later, he is supposed to battle with John Riel Casimero so prior to the cancelation of their fight, he is already doing some training for it.
Gaballo on the other hand is surely surprised and might have a few months for practice. I'm sure even with no scheduled fight after his last fight in December 2020, he still does his usual exercise to keep his shape and just began his advanced training when there's a hint that he might fight Donaire.