The date when a newly recorded security is up for sale is called the effective sale. In other words, it the date on which the shares will be traded for the first time on an exchange.
Points to remember:
After registering with SEC, a company can get their effective date within the next 30 days. This is the time taken by SEC for reviewing the Form S-1 submitted by the company.
A day before the effective date, the lead underwriter and company decide the number of shares to be sold and the prices at which it will be sold.