You should file your Trademark Statement of Use within the following time periods:
- Within six months of the day the USPTO mails you a "Notice of Allowance" (a conditional approval of the trademark application). This is a written notice sent after the mark is published. You can find the date that the Notice of Allowance was issued by visiting http://portal.uspto.gov/external/portal/tow and entering your USPTO serial number.
- Within a previously-granted extension period from the USPTO.