It's a 6 month wait from the date the blood which has given the positive titre result is drawn. If you have the blood drawn and the titre levels aren't high enough, you have to start over. My cats were vaccinated in early March and the blood was drawn on April 17th. I think I received the results within 2 weeks. The 6 month clock started on April 17th since the results from that sample showed titre levels were satisfactory.