Does being in the area of effect of a spell at the time of casting count as "entering"?
For example when casting Web:
Each creature that starts its turn in the webs or that enters them during its turn must make a Dexterity saving throw. On a failed save, the creature is Restrained as long as it remains in the webs or until it breaks free.
If it did not count it would imply that if you cast web on someone next to you, you would not get the chance to move the same turn with the benefit of them being restrained.