Quote Originally Posted by Throbert McGee View Post
"In the early '20s..."
"After the mid '60s..."
"By the late '80s..."
In - В начале/середине/конце 80-х.
By - К началу/середине/концу 80-х.
After - (???) После начала/середины/конца 80-х. (Better to avoid though IMO.)

No apostrophe.

As for age ("
in my 20s"), that scheme doesn't work in Russian. Possible translations: "Когда мне было (двадцать с чем-то)/(за двадцать)/(от двадцати до тридцати лет)".