That's when Reed and the Niners reached agreement on a contract to bring the tight end to the Bay Area, general manager John Lynch said.
In coming to San Francisco, Reed will be reunited with coach Kyle Shanahan, who worked as Washington's offensive coordinator from 2010 to 2013.
Reed spent one season under Shanahan after Washington selected him in the third round of the 2013 NFL draft.
Reed had 45 catches for 499 yards and three touchdowns in nine games that year before injuries ended his season.
For the Niners, Reed will get a chance to revive his career in an offense that has shown interest in finding a running mate to pair with George Kittle as it looks to deploy more multiple-TE sets than it has in the past three years under Shanahan.
Kittle, who is set to make $2.133 million in the final year of his rookie contract, has reported for camp and spent time with Lynch and Shanahan on Monday.
Ross Dwelley started six games last season and filled in for Kittle when he was injured, finishing with 15 catches for 91 yards and two touchdowns.
That season, Reed caught 87 passes for 952 yards and 11 touchdowns -- all personal bests.