I can see this concern. As of today, Jan 30, 2019, we still do not get any proper promotion trailer such as a series of custom battle play between different factions on different maps with different scenario (siege, ambush, etc.), kingdom management, starting stories. For a proper game industry practice, one should anticipate those months before the release of early access version to the public. And this sort of PR should continue as people start to play early access and the game being continuously updating, say, for another at least 6,7 months. Then the full version comes out. A rough counting would be, if TW starts to release gameplay videos tomorrow, we are expected to see a full release in about a year, Jan 30, 2020.
Seriously, 2020 release is not a joke. Unless TW does not follow typical pass which could be to release early access in a sudden, give very little promotion window and release the full game after a few weeks.