If you play 2 days a week and practice 2-3 days w/ one of those 2-3 days being with a swing coach you should be in the mid 80's within a year i'd say. I think golf gets fun once you get in the 80's...but the irony is, once you get into the 70's ...you dont have much fun in the 80's anymore
If you can just get to the point of hitting the ball straight...and you can get REALLY good at chipping and putting....you can shoot in the 70's.