Yep! Easter Vigil happens after sundown (or very close to) which makes it count for that Sunday. This is the same reason why Sunday Vigil masses are acceptable at ~6PM on Saturday nights throughout the year.
However, if you went to the celebration of the mass on Saturday morning; it’d be for Holy Saturday and would not count for Sunday’s mass. The primary factors are 1) The time of day the mass is said and 2) the liturgy and readings that are used for the celebration.