With Paladin Quests there are 2 extremes. Big-longass quests that dedicated what the game will be about for the whole group or reflexive/instant questing.
The first is a problem because it dictates a lot of things for the other characters, the second one breaks the quest move.
Here is an example of what might happen.
GM: there is a patrol of Dark-Elves approaching you on Lizard Mounts!
Wizard: spouts lore
GM: *tells something about extremly wicked and deadly Dark-Elf poison
Paladin: “In the name of Anor! I will slay these Dark Elves, a great blight of the land. And i want immunity to their poison and a sense of dircetion to them so that i can find them even in darkness.”
This is basically for 1 fight. The restrictions of holy vows won’t hit you as much. You will use mostly honorable tactics anyway i think and the others aren’t of much use either.
So just declaring Quests for a short instant bonus is a really cheap trick.
Nothing in the game says what is needed to dedicate yourself on a Quest. It could be a short Prayer between Paladin and God or a big ceremony requiring the Archduke of Canterbury (a sentient Owl-Bear that became one of Anors most holy crusaders).
Make sure you ask questions about these things in your first session to clear it up and create a precedent.