i always guess about a month, thats what im going off of with mine. I have two with dates and two without. one looks about the same time other looks closer. They get posty in the rear. sometimes they really drop, like they look fat then all of sudden looks skinny. If they are not that friendly they they all of sudden like you again that is a sign, or if they really like you then say nope dont touch me...or they could just drop kids when you are not looking