G. pulchra male - You will still have 5+ years to enjoy him.
Uhhhhhhhh...that is doubtful at best. Wishful thinking.
Mine went from a 1-inch sling to 4.75-inch MM in just over 3 years, and I didn't feed heavily or keep it in an extra warm place. If it's already an immature adult male, you might have another year with him before he hooks out, and then 12-18 months after that, unless you send him off for breeding (which wouldn't be a bad idea, considering how in-demand they are.)
Of course, if he's wrong and it's a female, that would be awesome for you.