The fine blog, Blogging the Boys has posted a schedule for the processes and procedures for teams as far as signings and contracts go. Thanks to them. This is user posted, so it is not official, but seems complete.
February 7 - Commencement of 15-day designation period for Franchise and Transition Players
February 11 - Waiver process begins
February 20-26 - NFL Scouting Combine in Indianapolis, Indiana
February 21 - Deadline for teams to designate Franchise and Transition Players
February 28 - Deadline for submission of Qualifying Offers by teams to their Restricted Free Agents whose contracts have expired and to whom they desire to retain a Right of First Refulsal/Compensation
February 28 - Deadline for teams to submit offer of minimum salary to retain exclusive negotiating righs to their players with fewer than three seasons of free agency credit whose contracts have expired
February 29 - Start of Free Agency and Trading period
March 17 - Begin Offseason Workout Program
April 18 - Deadline for signing of Offer Sheets by Restricted Free Agents
April 25 - Deadline for teams to exercise Right of First Refusal to Restricted Free Agents
April 25 - Deadline for old team to exercise Right of First Refusal to Restricted Free Agents
April 26-27 - NFL Draft in New York City
June 1 - Deadline for old team to send tender offer to its unsigned Restricted Free Agents or to extend Qualifying offer, whichever is greater, in order to retain rights
June 1 - Deadline for old team to send tender offer to its unsigned Restricted Free Agents to retain rights if player is not signed by another team by July 22