My Ds was a month early and was supposed to be "behind" for a year to three years while he caught up. We didn't pay much attention to traditional milestones because the docs always gave us the ones that were a month to two months earlier. They laughed at me when I asked if it was normal for a 3 mo old to turn pages in a book. I think they thought I was genuinely nuts.

DS walked his first steps at 10 mo and walked well by 10 mo 2 weeks. He had maybe 5 words on his 1st birthday but a huge receptive vocabulary and was understanding close to 100 signs and using probably 15-20 regularly on his own. By 14 mo, he was speaking in complex paragraphs that were at least 75% intelligible by strangers. People constantly snapped their heads around to see who was talking in the baby voice with adult words.

He has what we call "light bulb" moments where things just turn on- they don't build up, they just switch.