Well, if I think back, I can honestly say that she was still in utero and already giving me grief! LOL - Seriously, she was breach and everytime we had her turned to be ready for birth (which was supposed to be at home with a midwife) she would flip back over. I wound up having a C-section at the hospital with DR's I didn't know. It took two weeks to recover from the spinal headaches and all difficult child did was cry non-stop until she hit exactly 3 months old. Everyone said it was colic or my fault (I had trouble the first couple of weeks from my constant pain). But as if someone hit a switch she stopped crying at 3 months. She was a Johnny Jumper baby - always had to be moving, constantly. I still didn't think much of it really - she moved a lot in utero.
At about 2 yrs she started with some eye blinking and hair flipping, and again, we just thought it was a quirk. By 7 her rage attacks began and that finally caught our attention and we sought family counseling, eventually were referred to a psychiatric dr and then the rest is history.
So, I guess I could say we always knew, we were just in denial? I don't know, a lot of other stuff was going on along the way, like my separation from her bio-dad, moving 150 miles away from everyone, remarriage, etc.