Don't limit your book promo to launch day.
Your book deserves the build up. Mentioning it 90 days out or even further is absolutely OK. Especially if you include milestones: cover, title, back blurb reveals.
You can even think about getting your audience involved. Let them pick the title, or a character name, or if you can, let them choose between two covers. Get readers invested.
Not only is the lead up to release an important time to share the book's info, but post-launch is vital.
Self-publishing is not 'set it and forget it' territory. It's a constant need to stoke interest in the book. Update followers on sales, share reviews, and let them feel a bit of FOMO.
Consistency is key. Think of ways to achieve that before, during, and after release day.
I know it's cliche but being an indie author is a marathon not a sprint. Even more so when putting a book out to the world 🌎