How long is the drive from East Fishkill to Poughkeepsie during rush hour?

If you mean the City of Poughkeepsie, I'm going to say at least 20-25 minutes, perhaps more. Things can really slow down in this part of Dutchess County on the main roads at that time of day. I can even envision a scenario where things really back up and it could take you about half an hour to get from one to the other, if there's a lot of traffic and you're unlucky with the lights.