In our case they put up the signs the day after we parked (sunday) - hence the 2 tickets -- because according to the prior parking regs the car didn't need to be moved until Tuesday. To bolster our case, we requested work orders from the Dept. of Transportation.
I've beaten the one other ticket I received years ago. In that case the real challenge was getting the fine reimbursed. You can't reimbursed unless you have proof of paying the fine. But you can't get a hearing unless you pay the fine first. Therefore, if they overturn the ticket based on the hearing, shouldn't it be obvious you paid the fine?
Maybe, in these days of digital cameras, car-owners should just make a habit of taking a photo when they park their car in NY in case of eventualities.