Well I'll tell ya,
From my experience fishing the worm hatch has been about several different things. If the weather stays consistant and the water temps have a chance to warm up, then the hatch has happened. This May appears to be colder than last year and the year before. The hatch per reports from friends and others including myself has had the hatch as inconsistant and not as frequent. But, when the hatch has occured, it has been good. This particular area in RI I fish has the hatch during day light hours which is nice. It does occur, so I am told, throughout the Spring and Summer but at night time. Everything I have read and from all the people I have spoken to have the worm hatch as primarily an evening and night game. I try to get to the pond during the last 30 min of incoming to dead high tide and fish all of the outgoing. I time the tide so I am fishing in the late afternoon until dark. That has been the trend of the last few years for me. I am sure the moon comes into play but that's something I don't get too crazy about. In the salt in general I focus more on time of year, tides, water temps, bait, and from past experiences.
As far as presentation as I said in another thread, I don't dead drift the fly however I have heard of this method and it's effectivness. Some guys actually will use an indicator. This might be good if your fishing the mouth of a pond or estuary and there is a heavy current and the fish are sitting there hitting the worms as they come out with an outgoing tide. I like using a floating fly pattern that my friend came up with and slowly stripping it back. Deadly approach and very successful. I can't speak for other ponds and estuaries. I am sure they are all different in some way or another with some similarities mixed in.