It would take around three years, but depends on your feedings and water management and maintenance. As they age, their vertical bars gradually replaced with speckles, especially on the lower part of the flank, head, fins and tail. Some males replace their vertical bars totally with speckles, which can be quite spectacular. Species to go along with jags are those which can grow to about the same size and have the same temperament, like those boisterous Central Americans like red devil, midas, Friedrichsthalii, mota, haiti etc. Try not to put too much as they can grow really big. Alternatively, you can also put more of those smaller Central Americans like Nicaraguense, firemouth, convict, Cuban etc. Jags are not particularly aggressive if the tank is spacious enough, so not to worry. All the best!