Most of the time it's at least 1 year. This is a really bad time to get into the oilfield. Go back OTR untill the price of oil comes back up. If you should happen to find an oilfield job now, it's probably worse than OTR.
Most water hauling companies will hire just about anyone. That being said work is scarse. If you got a gig stay with it till the price goes up another 15 or 20 bucks. It might take until after the election or first quarter of 2017 for the price to get back up there. Good luck on your search.