Gaia's planned launch sequence as published on 06 December 2013, 13 days before launch, can be found below.
Gaia launched on: 19 December 2013, 09:12:19 UTC
Gaia Launch Sequence
Gaia will be launched on 19 December 2013 at 09:12:18 UTC from Europe's spaceport in French Guiana.
Below the launch sequence: