At the GEO Launch Services panel during the SATELLITE 2019 conference, SpaceX President Gwynne Shotwell, announced that SpaceX would be conducting their first Starlink launch on the 15 May 2019. Shotwell wouldn’t give the exact number for the amount of satellites on the launch, but did say that it would be “dozens”. However, the satellites on this mission will only be test-units, meaning they will not be fully-functional. An obvious difference between these test-units and the later production variants is the absence of Inter-Satellite Links (ISL).
The company are planning a minimum of two, and up to six operational Starlink launches following this test launch before the end of the year. These operational launches will be conducted nearer the end of the year, but the final number depends on how the initial test-units fare in-orbit.
In response to queries from Arianespace CEO Stephane Israel, Shotwell was able to reiterate that whilst they have 16-20 launches on their manifest for 2020, the deployment of Starlink is not expected to negatively impact any other customers. This is owing to the fact that SpaceX reportedly have the capacity to conduct 40 launches per year.