I agree with John. In all the years that I sailed on the Cheasapeake, I never worried about the tidal current. It's so small that it's not worth agonizing over. I think the most I ever saw was a knot, usually less.
My one experience coming up the Delaware Bay convinced me that it can be a huge factor there, as you say! We entered the Bay at Cape Henlopen, right at sundown. The tide was just beginning to flood, and we rode it all the way up to the C&D Canal, through the Canal, and down to Tolchester Beach in the Cheaspeake before it went slack at about 10 am the next day. We were getting a good 2 knot boost most of the trip. Quite a ride, but it would have been Hell if it were against us!