As of July 2014[update], the launch was tentatively scheduled by NASA for February 2015, with berthing to the station occurring two days later. However, as a result of delays in the launch of SpaceX CRS-5 this one will probably launch sometime in April 2015. In early January 2015 the launch has been tentatively scheduled for April 8, 2015. 
SpaceX has the primary control over manifesting, scheduling and loading secondary payloads. However there are certain restrictions included in their contract with NASA that preclude specified hazards on the secondary payloads, and also require contract-specified probabilities of success and safety margins for any SpaceX reboosts of the secondary satellites once the Falcon 9 second stage has achieved its initial low-Earth orbit (LEO).