I only have experience with one BCI, a female, and she did a lot of growing after 4 years of age. Best I recall, she did a lot of growing between 4 & 7 years, & she ended up over 7.5' long.

At least with a male, he should stay smaller, with much depending on locale & individual genetics, & of course, available food (which is not usually an issue for most of us here, lol).