Re: Countdown to the Age of Ultron
I know that in the Professor Xavier and the X-Men series, Pietro and Wanda are portrayed as being the same age as the X-Men. Professor X approaches them in Transia before Magneto finds them and offers them a place in his school, but they turn him down. In the X-Men First Class series, they are the same age as the X-Men. Wanda has a romance with Angel and hangs out with Marvel Girl.
In the early stories, Wanda and Pietro have no last names because the writers are too lazy to give them one. They don't start being called Maximoff until their adopted father Django Maximoff is introduced. After that, it is retconned to seem as if they were always calling themselves Maximoff.
In Avengers Origins: Scarlet Witch and Quicksilver, the twins are clearly portrayed as teenagers at the time they are impressed into the Brotherhood. Also, John Buscema version of her Wanda's costume as of Avengers 75 is retconned backward to her Brotherhood days.