Each rifle has a timeframe unto itself. It all boils down to what parts are requested. Some parts, like stocks, take 6 to 12 months to get in from foreign manufacturers. Some action manufacturers can take as long as 14 months to get an action to us to start work on.
Under a best case scenario if we happen to have all the parts for a build on hand (which is rare but does happen occasionally) a rifle can go from start to finish in as little as 6 weeks.
If we have to order everything from suppliers we work with regularly, 7 to 8 months is common.
We have a pretty good idea of timeframes based on our suppliers so can advise you to the best of our experience once we know what you are looking to have built.