iirc i was diagnosed 3 years ago (age 28). it wasn't a meticulous process though, and the psychiatrist wasn't exactly a specialist in asd. he did say he had diagnosed a few people before, and that supposedly his son also has asperger's, but that was about it. i had already been reading about it for a while, and i never really trusted his expertise, but for some reason he wouldn't prescribe me adhd medication unless he was convinced that i had asd (probably trying to avoid some kind of liability. stimulants are tightly controlled and only rarely prescribed where i live)
at first i told him that i had read about it and that i thought i probably had it, and asked him what he thought about it. he said "nah, you have good eye contact and good communication skills. aspies have nearly obsessive interests. like, collecting all the information about one particular thing, like you'll ask them what the flag of, say, andorra is like, and..." -- "it's like the flag of france, except the middle rectangle is yellow, and there's a crest on top of it. it's a tiny country in between france and spain, and they have a bizarre political system. it's the only country where catalan is the national language" -- "okay... you got me intrigued. we should look into this asperger's thing" 
other than finally getting access to ritalin, the most significant outcome for me was that, after being directly involved in the (rather short and informal) diagnostic process, my parents changed their attitude about me. they finally realized that i'm never going to "grow up", and that this is "adult me" already. it didn't really change much anything else to me, because asd is not a very pronounced thing in my case, and, most importantly, because i had already known for years that i had adhd, so that moment of "wow, so all this time, all my life, it wasn't my fault" had already happened
as a child, afaik, my verbal development was completely normal. according to what i've been told, what was noteworthy about me was that as soon as i learned to speak, i was already driving everybody crazy asking questions all the time
. but i did have a strong tendency to either play by myself or just watch others playing, instead of participating. never changed... i was also very fearful of strangers sometimes, and i'd refuse to talk to them even when my parents would tell me that it was okay (or that i should). i grew up listening to my mother telling me all the time, "son, you're not an island". she was wrong 