You probably don't want extended dev time for night shots, since the contrast will be plenty high already.

If you have two tanks put one roll in each, start the Delta, 4 minutes later start the Pan F.

Or, assuming you are working in a darkroom, and have only one tank, pre-fill your tank, load two reels with your film, making sure you keep track which is which. Put the Delta in the tank and start timing, after 4 minutes put the second roll in, put the cover on and turn on the lights.