In addition to the Livestream, you can also follow @ESA_ExoMars, @esaoperations and @esascience. There is an official Twitter account for @ESA_TGO, but according to ESA it won't be activated until "mission controllers have established contact with TGO following the fourth stage separation and acquisition of signal." I can't wait for that account's first Tweet! "Hello, world" doesn't seem appropriate -- will it say "goodbye, Earth" instead? There is not a separate Schiaparelli account; since the lander won't survive more than a few days, it would be cruel to imbue it with a personality. It's better regarded as one of the instruments on Trace Gas Orbiter.

Best wishes to ESA and Roscosmos for a safe start to their Martian journey!