Its usually 6 months. But there may be an alternative 'limited' lock up triggered earlier if the stock price is above a certain level continuously for a certain period of time.
"We and all of our directors, officers, and holders of approximately % of our outstanding stock and equity securities are subject to lock-up agreements with the underwriters that restrict their ability to transfer such shares of stock and such securities, including any hedging transactions, during the period ending on the date that is 180 days after the date of this prospectus, as further described in the section titled “Shares Eligible for Future Sale.”