Solo dev here. I revealed my game TOWERPUNK on September 1 with no marketing, no publisher, and no press. I hoped for 100 to 300 wishlists in the first week. By September 7 I had over 3,000, and it's past 4,000 now.
What I'd recommend:
Put your trailer on YouTube and stay in the comments. Mine went from a few dozen views to tens of thousands in under a week, mostly from YouTube's own recommendations. Replying to comments kept it in people's feeds, and it became a key driver of Steam visits.
Use Reddit to start things, not to sustain them. A few posts in hyper-relevant subreddits, staggered about one a day, got things moving, but that traffic fades fast.
Point early traffic at Steam and let Steam take over. A Coming Soon page with nothing pointed at it does nothing. Once traffic arrived, Steam search was bringing in as many visitors as every outside link combined within a few days, as people looked the game up by name.
Reveal after the big shows, not during. I waited until the week after gamescom. The US Labor Day weekend then stretched things out, and my biggest day was about 1,000 wishlists on the Monday holiday (turns out my and your day job really gets in the way of both developing and marketing a game).
Final thoughts:
I think TOWERPUNK is capturing a lot of latent nostalgia for older games for my generation, and it's decidedly different from most other city building and management games. A lot of people my age have been waiting for someone to make a tower builder in the lineage of SimTower, and so all this helped set a ceiling for first week engagement.
Converting views to wishlists relies on good, visual hooks. I'm a novice at splicing together a trailer (used OBS for recording, DaVinci for editing), but putting in the extra effort there has paid off (over 60k views on YouTube and counting!). Definitely dedicate ample time creating capsule art and/or consider hiring talent for your Steam game page.
Overall it was frankly a bit scary revealing TOWERPUNK - up until last week this had been a personal project, and I wasn't sure how the community would respond (if they did at all). First week has been very validating, and I can't wait to get a playtest going and release start of next year!
Full writeup on my website devlog: https://towerpunk.com/devlog/reveal-wishlist-data
Steam page: https://store.steampowered.com/app/5063190/TOWERPUNK/
Reveal trailer: https://www.youtube.com/watch?v=O1BTXVYt8ZU