how long do you have after buffing the floor to apply a water based finish ? what length of would it be okay to finish over ?

I believe you can wait any amount of time after buffing. I think the only things that could make you have to buff again might be foot prints on the floor if it has not been coated yet.

technically, u should coat the samde day u buff the floor..as humidity and environmental chnages can effect the grain and make it open again

I always buff right before putting the finish on. If I finish sanding at the end of the day but am not coating till the next day I buff in the morning.