The week before
Write the tagline, the description and the first comment. Prepare a 60-second demo video or a GIF. Tell your existing users the date and ask them to come and say what they think.
On the day
Post at the start of the platform's ranking window. Stay online and answer every comment, including the critical ones. Replies keep the listing active.
After
The listing stays on the platform after the ranking day ends. Add the badge to your site if you want it, and link to the listing from your launch post.