Most of the points brought up already cover a lot of ground, but Mogaoscar’s point is very important. Not only does it help with the good advertising points already brought up, but a lot of people who could buy this think this has been and will be a great year (or at least next few months) for games. You want to announce it with at least a month between the announcement and release.
Next, you want to market on gaming sites like Siliconera (which does lots of VN coverage) and Gematsu if they will let that happen. Considering that Siliconera has done coverage on Key polls and posted most of the updates from the Clannad KS when it was running, that shouldn’t be a problem. MAL and ANN and an advertisement on the Clannad KS page are still good ideas too, especially since the second season of the Little Busters anime is ranked so highly. We all know how much rank factors into some decisions.
I think you should also want to keep promoting and marketing it as the release date gets closer. Persona 5, for one example, has constantly had video and DLC coverage on Siliconera. That not only keeps their title in the news so that people know and don’t forget when it is coming out, but it entices them to buy it or to change their priorities around to play it sooner. You can possibly entice them doing things like by showing some small videos of your translation, announcing that the OST will be available for purchase, or doing an interview session (that might mention lots of their previous work).
Marketing is about getting people who don’t know that your product exists or that don’t know that they want to buy it to buy it. Little Busters is a lot less known than most other games and anime are, so let them know.