J.R. Smith has until June 26, two days before the NBA Draft, to give the Knicks notice on opting out of the final year of his contract worth $2.5 million, according to an NBA source.

If he doesn’t exercise the opt-out clause, Smith will be a Knick next season and could get a long-term deal with the club after next season. Because Steve Novak is a good bet to depart, the Knicks want Smith back as a sixth man — and possibly to play some point guard despite his wretched shotmaking in the Knicks’ five-game first-round knockout by the Heat.

“Without a doubt, hands down, I wouldn’t want to play anywhere else,’’ Smith said on Trash-Bag Day Thursday. “It’s the greatest place to play. It’s the greatest city in the world. This is my ultimate home.’’