Hi Baba,
I didn't know until he "crashed and burned" in 2nd grade, but looking back -
eye contact in the first 48 hours -
At 4 weeks when I went to visit my co-workers with him in the baby sling, as I spoke to them, they reported that he observed me carefully, and moved his head in the same way and to the same beat, including mirroring facial expressions.
He knew his letters at 2, without being taught.

Best book by far is 'Deb Ruf's Losing our Minds, Gifted Children left behind.' You can also call her up for a phone consult.

Document everything on video camera! With ages.

I reccoment talking to her as though she knows what you are saying, and limiting the amount of TV violence that on when she's within earshot - real or pretend. I would also keep an eye on her sleep habits - it can be extra hard for these kids to unwind - we didn't use any rituals - just kept him up till he colapsed, or nursed until we drifted off. I would be more proactive now.

How old is she now?

try these articles -
http://www.davidsongifted.org/db/Articles_id_10223.aspx
http://www.davidsongifted.org/db/Articles_id_10284.aspx
http://www.davidsongifted.org/db/Articles_id_10299.aspx
http://www.davidsongifted.org/db/Articles_id_10082.aspx

Best Wishes and happy baby -
Trinity