Williams' camp had argued his retirement should take effect from the time he told then-coach Dave Wannstedt of his intentions, which was July 23.
Williams still will have to serve a four-game suspension for his three violations of the NFL's substance-abuse policy, but he will be allowed to practice and take part in the team's five preseason games.
In other news:
-- While Williams now seemingly will be in camp on time, fellow running back Ronnie Brown might be in a different situation. Brown has yet to sign a contract and his agent, Todd France, apparently wants to first see what San Francisco's Alex Smith -- the top pick in the draft -- signs for first. With the 49ers not opening camp until July 28, that complicates matters for the Dolphins, whose first practice is Monday, July 25.
-- Seventh-round pick Kevin Vickerson is not exactly scoring points with his his new team. According to published reports, the defensive tackle from Michigan State has been late to several meetings, validating pre-draft concerns about his commitment. Considering the Dolphins spent next year's fifth-round pick to take another defensive tackle, Manuel Wright, in the supplemental draft, Vickerson might want to turn it up a notch if he wants to be a member of the Dolphins this year.