352.4. If a card requires you to specifically choose one or more Game Objects , that choice is made now.
352.4.a. This does not include cards that affect one or more Game Objects based on criteria. Example: "Stun a unit at a battlefield" is a Choice. Example: "Kill all gear" is not a Choice.
352.4.b. This does not include making choices for Triggered Abilities of permanents, even if those abilities trigger when the permanent is played. Example: A unit with a triggered ability that says "When I'm played, kill a unit" does not require you to choose a target as it's played. The target will be chosen when the ability triggers. See rule 375. Triggered Abilities for more information.