RE:No. Shore, How Long?
Now that the fish are blasting through the canal it won't be long. Squid are reported in Plymouth, and Boston Harbah should be coming alive any day now.
As far as reliable fishing, I always use Father's Day as a general date to start thinking about north shore stripers. Of course they show early but reliable wading trips start in early June from my experiences.
It might be a good idea to listen for the Salem Harbor guides to start tooting their horns and the Merrimac will be right behind it.