Here is a "copy and paste" from an attorney websit

Here is a "copy and paste" from an attorney website, for additional information related to the quiet period for publicly traded companies, (not an IPO).

Guidelines for Public Companies

Although the rules and guidelines for public companies are a little grayer, the goal remains the same for these quiet periods: avoid selective disclosure of material information. Determining a good time to begin your quarterly quiet period depends on when your finance and accounting departments have finalized or nearly finalized the quarterly results, and given management a good idea where business performance will land.

It is important to take your quiet period into consideration when planning non-deal roadshows or scheduling investor calls because management will be limited in the information they can share. Investor events are much more productive when hosted shortly after an earnings call because management has more leeway to answer investor questions.