Jitte de Umezawa

If the "target creature gets -1/-1 until end of turn" mode is chosen, the target creature must also be announced.

If the Jitte is moved after the "+2/+2" mode is announced but before it resolves, the bonus is given to the creature that is equipped when the ability resolves.

If the Jitte leaves the battlefield after the "+2/+2" mode is announced but before it resolves, the bonus is given to the creature that was most recently equipped once the ability resolves.

The ability can be used any time Umezawa's Jitte's controller has priority — only the "target creature" choice has additional requirements. Choosing the "Equipped creature gets +2/+2 until end of turn" mode does nothing if the Jitte isn't equipped to a creature when the ability resolves.

Umezawa's Jitte's activated ability generates a modal choice. The choice is made when the ability is activated.