I just did this trip last Friday (and continued on up to Rhode Island) - The tide and the wind were against us toward the southern end of the bay and we struggled to make even a couple of knots progress. I am not sure we would have been happier waiting around for a better time to go though - So I second the advice to just go. What I would say, however, is that there is a LOT of big ship traffic on the Delaware and it would be easier to do it in the daylight - We did it at night but you need to keep a sharp lookout -
Radar helps a lot. Pea soup fog rounding Cape May was a bit nerve racking but OK if you pay attention to your
GPS.