My son and I ran an errand last weekend so of course we took a detour by PI! The place was a mob scene and the fishing was so/so. We saw five guys out on Joppa as we drove by.
Low tides are late this weekend so either the beach crowd will join you or the morning fishermen would have left by then, it could go either way.
The bait has been much thicker up river, we stopped around the docks at Nbypt and up and there was bait everywhere. Some locals informed us that schoolies were busting everywhere around Stripers Restaurant the night before. I suspect that with the abundance of bait upriver that Joppa would have a lot of fish on the ebb. The low tide is at 1.3 ft so it's not extreme by any stretch, just get off there with plenty of time once the incoming starts to run hard.
You'll have a high tide around dawn so you might consider the oceanfront, fishing around the jetties placed along the beach to preserve the sand from the mouth down to the corner near the baitshop. I'd go to that option just to get away from the crowds, and there should be some fish in the wash this time of year.
If you know any accesses upriver they might be worth investigating this weekend. Another option would be to try Hampton on the south side of the bridge from the fisherman's terminal all the way around to the beachfront rocks. It's not always as productive as other areas but it's beautiful and there's always a few fish around.
I havent' done the end of the refuge yet but I suspect the water in the Ipswich area is very cold. If you could get up into Plum Island sound near the shoals and flats (north of sunset beach) you should do well; so the PLum Island river should be holding some fish too as far as crowdless opportunities are concerned.
With the outgoing starting at dawn, consider the Salisbury side from the pick east to the jetty base. Fish deep and slow with sand eels patterns in the seams between current and eddy and you should score pretty well.