Well, I am fairly confident my DS will test out as gifted, but I'm not sure what level at this point. He's now 23 mos.

First signs for us:
extremely alert/attentive baby.
Repeated the word "hi" back to DH at 4 weeks old,
attended to books well from 3 mos on, and turned pages at 5 mos.
Refused to crawl- seemed "insulted" by it- wanted to walk upright desperately and did so at 8 mos, ran very well by 10 mos...It's so hard to accurately describe his frustration here- but I have videos of him arching his back to a stand- he definitely was MUCH happier once he was walking.
First word "cat" at 6 mos 3 weeks,
Could point to "nose, hat, mouth, eyes, chin, cheeks, ears, toes" by 7 mos,
Used to open the cabinets at 8 mos and look at the screws that hold on the knobs- could use a screwdriver by 14 mos, and LOVES tools/mechanical things. Built a mini simple seesaw out of scrap wood (no screws/nails, just a simple fulcrum)
Started to ID letters at 14 mos, sight read first word (that I know of...) at 18 mos.
Knows colors, shapes, can count item up to 5 at 20 mos...
At 18 mos had vocabulary of 500+ words, and now at almost 2 yo. I'm not sure, has to be over 1500, knows words like exhaust, vulture, dangerous, slippery...

I'm a bit lost as to what to do with him somedays as he's SUPER active, energetic, and seems to have some psychomotor overexcitability...

Thanks for this thread, feels really good to share this in a safe place.