Historical Rules · 14 June 2019
Rule 208.3a
Official source text from the 14 June 2019 Rules release
If an effect would be created that affects the power and/or toughness of a noncreature permanent, that effect is created even though it doesn’t do anything unless that permanent becomes a creature. Example: Veteran Motorist has the ability “Whenever Veteran Motorist crews a Vehicle, that Vehicle gets +1/+1 until end of turn,” and it’s tapped to pay the crew cost of a Vehicle. This triggered ability resolves while the Vehicle it crewed isn’t yet a creature. The continuous effect is created and will apply to the Vehicle once it becomes a creature.