The NFL has announced the OTA and minicamp schedule for all 32 teams, including the Miami Dolphins. Here's the scheduled for the Dolphins:
Rookie Minicamp: May 4-6
OTAs: May 22-24, May 29-31, June 11-14
Mandatory Minicamp: June 19-21
Here's the NFL's explanation of how the OTAs and minicamps work:
Clubs are permitted to hold a rookie minicamp on one of the first two weekends after the NFL Draft and conduct one mandatory minicamp for veteran players. Clubs with new head coaches, however, are permitted to conduct one additional voluntary minicamp for veteran players. There is no restriction on the number of minicamps a club may hold for rookie players.
Obviously, Miami falls into the category of a team with a new head coach. However, the date of any additional "voluntary" minicamp for veteran players has not been announced.
Additionally, the rookie minicamp can include any one-year veterans with less than three games on the active/inactive roster or injured reserve.