The minimum time to submit a sample is 12 weeks and 20 ejaculations following the procedure. There may be times where you wish to wait for longer. The most common reason a vasectomy is carried out whilst a man’s partner is pregnant. In this case it is usually advised for a 6 week period of abstinence post delivery. Therefore men can wait until this period to submit a sample. The longer you wait, the more likely it is that you will provide a negative sample. Information about the logistics of semen collection can be found here at the bottom of the page.