There is no exact timeframe as it depends on a lot of variables. A lot of it depends on how popular the specific model/floorplan is. They will not do a production run until they have enough of that specific model/floorplan to make it cost effective. 6 to 8 weeks is the canned answer.
Last October we ordered the 23WS and the order was officially entered 10-23, it arrived at the dealer on 12-11 and its build date was 12-2. 5-1/2 weeks until built and at the dealer in 7. When we ultimatly rejected that particular unit the dealer had the rep on the phone at the time and he stated 8 weeks again. That order was placed on 2-25.
The dealer can call Rockwood and they can tell him the exact date that production is scheduled as long as it is scheduled. If they do not have enough orders of a particular model/floorplan it may not be scheduled. Remember Shamrock also comes into play as they will run those at the same time. Mainframes Shamrock 23WS was built 12-1, the Roo 23WS they built for us was built 12-2. As far as I know they have not produced any 23WS models since that time in early December as I have not seen any new ones pop up online anywhere.
The dealer is the only one who can tell you and only if he takes the time to call the rep.