The San Francisco 49ers kick off their organized team practice activities (OTAs) on May 21st. Those will run through June 7th, followed by mandatory minicamp June 12th through 14th. This is as important a period as any in the offseason. Players have been going through classroom work, and had individual work on the field. OTAs and minicamp are when teams really get to implement the playbook and get players ready for training camp.
This also means players can take a step forward in competitions for either a starting job or simply a chance to make the roster.