The controlling factors are access to deer and keenness. If you lack one or the other, you will be limited. If you have both sky's the limit, I guess.
My nephew started his journey two years ago.
Joined a rifle club, and his dad helped him with access to stalking. He got his FAC about 20 months ago, picked a 2nd-hand T3 .308 up the afternoon his certificate dropped on the mate, and shot a Roe with it that evening.
He works 60+ hours a week running his own business. He shot nearly 160 so far, got his larder and butchery all set up as well... he's keen..
He's already done his DCS1 & 2.
I call it youthful enthusiasm.