How far in advance to book Las Caletas in Puerto Vallarta

Does this excursion sell out? How far in advance do we need to book tthis?

I would just book it. You can always cancel if you change your mind. The excursion I wanted in Cabo is wait listed which bums me out. I'm on a sold out cruise so I guess it all depends on that. I already reserved and paid for the Caletas one. There's only 19 spots left on my cruise. good luck

Thanks!:)