Age/weight question

Okay so I'm new to Boas, I just got my first one last week on Thursday and sadly at petco they had no flipping clue how old this guy was....so you can imagine my frustration, Anubis, he's a Columbian Red Tail Boa. He weighed in at 80 grams and is at 15"... I know every snake grows differently I'm just hoping to get a rough guess.

15 inches is pretty young - although males tend to be smaller, my female just turned 1 year last months and is 30 inches, so i thing you can safely estimate 6 months +/-

I would say he is most likely a 2017 at that length...