So as a bit of fun, I had a thought experiment.

Assume your Warrior of Light somehow manages to go back in time to the beginning of their adventures with full knowledge of the events to come up until 5.55 (or however far into the narrative you are), what changes would they make, and what outcomes would you expect as a result of those changes.

Would you save anyone, kill anyone, not drink anything?

Personally, I imagine if I were the warrior of light, I'd likely try to keep the changes as minimal as possible, to prevent screwing with my knowledge of the events to come. Like, if I stopped the events of 2.55, that could stop the WoL from seeking refuge in Ishgard, putting a hamper on dealing with Thordan/the Ascian's/Nidhogg's plans, etc. (to say nothing of the course of events relating to the First)

So I'd only risk doing small things here and there to save a life or two, request that they avoid the limelight and hope that doesn't bite me in the rear. Maybe get Haurchefant's shield reinforced (which would 100% bite me but whatever) or ask Minfillia to have some of the scions to help me with some tasks while I deal with Titan.