Around 3-4 months. Now she has some longer parts (the hair that didn't fall out) that are long enough to put into pigtails, and shorter parts (the hair that's growing back in) that stick out a little bit.
My dd and I both started losing hair when she got to be 3 mos old.
My hair is falling out in handfuls, and hers is falling out in a circle around the crown of her head from where she turns her head from side to side while laying on her back. The rest of her hair is super-long.
We must be the exceptions! Neither of us lost any hair! He just kept growing until he had a full head.
And I cut mine & donated it to locks of love, but even short, it didn't fall out. I will say this, being pg really changed the texture and overall identity of my hair. Does that make sense? It's like a whole different head of hair!