I have never been to Ankara. But there are return flights to Ankara from Tehran (Mahanair and Iranair) on Sundays, Tuesdays, Thursdays, and Fridays. You can check out their website to have more information in detail. And there also exists a hotel named "Midi Hotel", five minutes walk from the Canadian embassy, you can google it. Before Nowrooz, it is still not high season and I think you do not need to reserve a seat on a specific flight or book your hotel in advance. I guess that you can go to Ankara airport right after you receive your visa and get the first flight back to Tehran. So there should be no place for worry about the time.