After buying this, I will have completed my collection.
Once I get my black belt in Karate, I will have mastered all martial arts.
Once I eat at this restaurant, I will have eaten all kinds of foods.
Once I finish The Deathly Hallows, I will have read all books by J.K. Rowling.
If a flying spaghetti monster pops into existence in my backyard, I will have seen everything.