Around three days,If my calculations are right:
1: Wish for two or more of the heavy jobbers z-fighters to come back to life.Keep the current villain entertained that way (which fighters to choose depending on how powerful this bad guy is)
2: Send Goku (and more than probably Gohan) back to the afterlife to train with the God of The Week ® to train him.
3: Once revived z-fighters are done getting beaten up enough and Goku finished with his training,send him back to Earth and have your Ultimate Sayan Next Powerlevel Battle.
4: Do ANOTHER muddafacking Genkidama®