Marketing (and I’m just talking about the general idea of talking about your games and making people know about it), should be thought from the beginning of your project. Don’t take it too seriously if you’re not into it, but think about it, start gathering ideas, start structuring it, and planning.
One key point in social medias in particular is regular posting. So, by the time you have an more or less exact day of release of your game, start planning your tweets, facebook posts, instagram screenshots, stories, dev logs, etc.
From the time you decide to start posting about your game, to the day of its release, and after that, you should be able to post things on a regular basis, i’d say several times a week, not spamming people, but not leaving blank space of weeks. Follow people who you’re interested in, in terms of your game, and like their interesting posts, their own games too. Join facebook groups, and websites (not scams though).
Also, be careful about posting things that are not polished, that look amateurish. It’s interesting to post artwork, especially once the game is close to release, but it’s more debatable to post prototypes screenshots, as it can give a false first impression of your game. And many people don’t like to think further than their first impression.
Here are several ideas about what to post:
But remember: don’t spoil too many things, including details about your map, advanced enemies or characters, powers, etc. Save a lot for your first demo or release.
Time to post on social media/emails: (some sites are more complete/up to date)