Just like a normal ability.
When changing the level of an Aura Ability, there's a delay before the new level effect takes place. Let's say you have a level 1 Aura Ability. You raise it to level 2. There's about 3 seconds delay before the Small Buff Icon displays the level 2 information.
Is it possible to remove the aura buff and then increase the level? Would this speed up the delay?