Yes, there are many successes of day 3 transfers. As a matter of fact, some clinics exclusively do day 3 transfers b/c they feel that the uterus is the best place for the embies to thrive.
I hope the 2ww goes by fast for you. Are you going to POAS? I know that SG makes you wait the entire 2 weeks, but if you have a positive stick, they may move it up a day.