If a hit is guaranteed to make an enemy Vulnerable, does that first hit that applies Vulnerable to the enemy also apply all damage bonuses/effects vs Vulnerable enemies if say you only hit them the one time, like it makes them Vulnerable and also procs anything that effects Vulnerable enemies, or would the initial hit just make them Vulnerable and only the follow up hits account for any bonuses against Vulnerable enemies?

For instance, if I hit say a skeleton with something that makes them Vulnerable while using an item that has 12% Dmg vs Vuln enemies, if I only hit them once, would I get the 12% Dmg alongside making them Vulnerable at the same time, or would I need to make them Vulnerable with the first hit and then hit them a second time to get the 12% bonus to proc once they’re Vulnerable?