With a June/July pre-dawn departure from Essington with favorable currents and tides a one day dash to Cape May before sunset is possible but that strikes me as to much work.
I take an overly relaxing 3 days; Essington-Delaware City- Cohansey-Cape May, cutting out Delaware City would still be a relaxing 2 day trip.
A Cohansey departure can be scheduled to arrive at the entrance to the Cape May Canal near slack at the canal entrance. If arrival is early for slack and the wind is not out of the west then anchor
off Higbee Beach until slack, or just power through the rock jetties. After the ferry terminal the canal is OK even with power boats zipping by.
Try to avoid the canal entrance on summer weekends when the power boats power up as they transit between the rock jetties. The entrance is a lot narrower than the C&D.