Answer: One month is the usual recommendation however, I have had couples tell me (I am not making this up) that they had sex the evening of the procedure and that the reversal resulted in a baby.

The microscopic reversal is watertight from the microscopic sutures (meaning conceivably that tube is patent from the get go and that sperm can traverse the reversal without leakage) however there are other areas of the procedure that need to heal as well. So the one month of waiting is for everything to heal properly- from the skin incision, to the vessels that surround the vas deferens and the repair itself.