I'd be interested in seeing what people say, but if they don't answer you in time, I'd do one of two things depending on the actions you've already taken:
1. If you haven't changed anything yet: I'd create an additional wait step, flow all new contacts through that one for 14 days and maintain your contact in the current flow.
2. If you've already changed the wait step and are wondering what will happen: then I would modify the path of your current contact to have them pass through a wait calendar date driven wait step and have all your new contacts flow through to your 14 day wait step.