How long to fix forward neck?

Guys, back when I was 11 all the way up until I was 16 I was an absolute addict at video games and my poor posture while playing upto 12 hours a day means my forward neck and anterior pelvic tilt still remains 3 years later which is annoying as I’ve made such good gym progress but still don’t look as good as I want to because of this posture.

How long does it take to fix forward neck? And any advice or exercises you recommend?