It is not a best practice whatsoever and I'm not sure if it will work, but you can try modifying your wait step to a certain date, like next Tuesday. I myself would let this one go, but when you create another Nurture Campaign try to avoid those dates in your planning phase. The ability to choose dates to wait til makes this process a lot easier than in the past. We were tired of counting days.
What I am not certain about is how the Leads will react if you modify a flow step that they currently reside in, but if you modify any future flow steps the campaign should continue without a hitch. Just like switching an email out, modifying the Wait step should have no affect.