Rocket number two has now made several flights attached under its mothership. Now Virgin Galactic have made enough these flighs so that the next step is to do glide flight. Then the rocket is dropped about 15 km altitude and it will glide back to the aipport. These flights are needed maybe ten, after which rocket-powered test flights can be started.

The first glide flight was planned to happen Nov 1, 2016 but it was cancelled due to strong wind.

More info-> Space.com