The NFL season is set up so that veteran free agency precedes the draft by about 6 weeks.
Two key dates to be aware of in free agency are 16 March and 18 March. On the 16th, the “legal tampering period” opens, in which teams are allowed to negotiate with agents in advance of the start of the new league year. The 2020 league year begins at 4pm (New York time) on 18 March. The first deals of the free agent frenzy will likely become official around 4:01pm.
Of course, it’s an open secret that a lot of preliminary work is done during the Combine that has just ended in Indianapolis.