This milestone isn't measured in months or years or time, but in events. For instance, one of my nursing goals was to make it to the point where I'd have a talking nursling. She talks now, in big sentences (but still doesn't tell me how the milk tastes, lol). And she has a sense of humor. I don't usually wear a bra at home, but if I happen to be wearing one and we get into position to nurse, I'll lift my shirt, and she'll dive right in FIRST and THEN notice that there's a bra in the way, and sit there and laugh at it. She also thinks it's hilarious if I lift my shirt, but "hide" the nipple from her and playfully try to get her to latch onto the bottom of the boob.
But anyway, today another milestone was reached. She brought me her toy horse and wanted me to nurse it. I was in the middle of doing dishes, so I told her that she could. She thought about it briefly, then raised her shirt and put the horse in position. Then she went back into the living room, and came back while "nursing" a baby doll. I can count on one hand the number of times we've even talked about HER being able to nurse eventually (or pretend nurse now) so it's neat to see her remember and/or make the connection.