Yeah, and I can see myself dying If I jump from 4 floors. But that doesnt mean I can see the future.
Luffy had no haki at their, he trained 2 years with Rayleigh and then trained with Rayleigh, and he never had a hint or flashback of himself during that time, nothing shows that it was future sight, it just shows he knew how dangerous it was with the intentions of MIHAWK ,
No dude. He first thought attacking Mihawk but then he saw the future and moved to bazooka the floor. Oda bothered to draw a panel of what Luffy saw.
Dude you clearly didn't understood how haki works. It needs extreme situations to unlock them.
Luffy against that bufallo is a hint to his CoC but not necessarily his power being unleashed. The extreme situation was at Impel Down when he scared all wolfs attacking him and Mr 2. And again at Marineford when he knocked out a bunch of marines to avoid Ace execution.
Coby unlocked CoO at Marineford too because it was extreme situation. Usopp at Dressrosa same shit. Zoro at Alabasta.
But look what Zoro does right after he rested from Alabasta fight. He trains to control it. He was able to use it in a desperate moment but he couldn't control it yet. Probably the reason he wasn't able to cut Enel(and for not knowing the full extension of this power).
Luffy clearly unlocked FS back at Marineford. But couldn't control it. That's why he quick learned how to control against Katakuri. He already had it unlocked just needed to train for control.