Your character must immediately carry out the instructions.
The spell is based on lesser geas, which says:
The geased creature must follow the given instructions until the geas is completed, no matter how long it takes.
There's not much wiggle room there. In particular, you can't say things like "okay but I'll do this other thing first". You have to follow the instructions immediately.
The instructions don't require you to start a one-against-three combat.
The spell also notes:
A clever recipient can subvert some instructions.
So you do have some ability to interpret the best way to carry out a given instruction. For example, you might argue: "well, if I attacked the other three characters right now, I'd just lose, and that wouldn't accomplish killing any of them. The right thing to do should be to continue fighting the enemy as though nothing had happened, and then kill them in their sleep when I'm on watch tonight."
Or even: "killing my three friends tonight wouldn't be a good way to kill all the allies of Aura. I'll need to become some sort of deep-cover agent, and formulate some sort of long-term plan to betray everyone at once. I sure hope I can find a way to do that before the one-day-per-caster-level time limit runs out and the spell goes away!"
You'll note that these developments are actually a lot worse for the party's success, and arguably are less fun for you as well. The optimal way to play this, from the point of view of the party's victory, is to run straight at the most heavily-armored character shouting "GUYS I'M MIND CONTROLLED I NEED A DISPEL QUICK!!!". This is probably also what your GM is expecting you to do.
The GM has a lot of latitude in this.
Although your character can (and should) search for the least bad way to carry out this instruction, the GM is ultimately the arbiter of what counts as "finding a creative way to obey" and what counts as "stop splitting hairs and start making melee attacks against your allies". If the GM tells you which interpretation of the spell you have to use, you have to use that one.
You've asked for practical experience. When my PCs get mind-controlled, I usually pause the action and I tell them: "your character has to do the thing, but your character is frantically searching for ways to make this less bad. Each turn, you can tell me what you're trying to do and why you think it should count as obeying the instructions. If I don't agree, I'll take control of your character for that round and have you obey the instructions in a straightforward way."
I remember one time when my own character was mind-controlled and made to believe that all his allies were undead and needed to be destroyed. I immediately answered that my character was using turn undead at them, which did nothing except waste my character's action. A better move would have been to use healing magic on them, expecting that the healing magic would harm the undead.
