I think I asked the same question here a long while ago. I have made many blunders of the same sort as the ones shared here, and have read the pbs milestones specifically to ascertain how to communicate with others about what their dc are likely doing.
While I was chatting with friend on the phone, she exclaimed to her ds (sweetly), "What
are you doing? You're TWO! You just opened the door? Are you finished sleeping?" I did some mental acrobatics to figure out the "you're two" part and assumed that she must have meant that he needed to sleep longer or that he was already aware that he wasn't allowed to open that door (which didn't make sense to me either, but seemed somewhat possible given my friend's parenting philosophy).
She then asked me when my dc started turning door-handles, which I took as pertaining to the subject, but not to what just happened. I told her that once they can reach them, they open them.
This is early also, which she knows, because they are all 95th and higher percentiles for growth, so reaching the handles happens somewhere in the range of 13-17 months (varied torso and arm length).
She wasn't impressed and told me that her dd didn't open a door until she was 3.5 yrs old and that it isn't usual for children to do so until about three or so. I had no idea. I hadn't even considered it in terms of milestones until she pointed it out as such. Ooops...
Then last night we were talking about the dangerous jumpers in our home and I told her about the only rule I've ever made that limited acquisition of physical skill, which was for ds3. It was that he was only allowed to jump off of the seventh stair and no higher. She asked when I made that rule, and I had to ask dh and we worked it out and surprised even ourselves when we realised that that rule went into effect when ds3 was just 18 months old.
Ds4 is currently climbing our six foot ladder efficiently and walks up and down stairs without a railing, and has been practising jumping off of 3+ft platforms and swivel stools (aaahhhh!!!!).
I shared this because she was admonishing me to not make limitations on them with this- although I'm not sure why she presumed that I do other than that we haven't been able to spend time irl together except for vacation visits for years. I used the example to illustrate the only rule I've ever made; I totally and unintentionally diminished her excitement in telling me that her 2.5 yr old is now frightening her by jumping off the second step of their stairs.
Sigh... If she were not an ece, we might talk about other things than child-rearing and milestones, but this is her interest and while I am not otherwise as apt to share as she is because of so many negative experiences I've had with that, this is our only lasting commonality. I guess that she hasn't disowned me means that she's coping at least. That and she and her family are moving across the country to live near us... I love her. She's awesome, and I don't know how to stop hurting her confidence and excitement. Maybe it will stop once she sees how we live on a daily basis because then I won't have to correct her assumptions about my mothering.
Maybe I'll start a thread about that and stop hijacking...
ETA: I usually just ask her and say nothing about my own dc unless unrelated, but she called really late and my filter was full. Ugh, now I have lots of work to do...