I have fished the reeef the last 3 spring, 1st or 2nd week of April, the fishing is stupid good. There are many access areas for floaters and the signage is good as to what is private vs public. Several shops provide shuttle service too.
http://www.blm.gov/pgdata/etc/medial...latteGuide.pdf
I have never dry fly fished in April but pine squirrle leech, san juan woorm, always seem to be on the menu.

good luck