depends,some are gifted with the ability to listen n play,if that person is good,it would take maybe as little as 5 minute..

haha! me?eh,sort of no choice,playing in church so have to be quick to learn,sometimes even immediate for chords playing,instant can la,but if want like those abit more classical,takes longer time,but i hate classical music i once tried playing casiopea vs t-square fightman,took a week to get the precise notes

Depends on how precise it has to be learning is quick,perfecting takes time n lots of determination