Pom Klementieff was 20 in After Him when she played the character 'Emilie'.
That was over 17 years ago in 2007.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 38, and has starred in 33 movies in total, 31 of those since After Him was released.
In After Him, I think Pom Klementieff looks: