From my experience, I would say length first year and bulk second year. Scorch was about 16" at 9 months and grew to 20" by the time she was a year old and now at a year and a half she is not grown in length in the last 6 months but is getting wider, her head is growing allot right now, she is getting ready to shed it again and it just shed a month ago, which is a sign of growth. I think their growth rate has allot to do with husbandry and how well they will eat as well as genetics so there is no definitive answer as far as when they stop growing in length. I think the more they eat the faster they grow and sooner they stop growing. I hope that makes sense.