Products go live on a set day and people vote, comment and try them. Most visitors arrive on the day you are featured.
Schedule it for 12:01 am PT, Tuesday to Thursday. The comments in the first hour shape the whole day.
Maker's first comment: The first comment on your own launch. Who you are, the problem you had, what you built, what it does not do yet, and a question people can answer.
Link your App Store or Google Play page, or a landing page that links to both. In the workspace, Groivo gives Product Hunt its own App Store campaign link (ct=) and Google Play referrer, so downloads from it show up in App Store Connect and Play Console.