how long on average does it take for a jaguar cichlid to reach about 150mm (6 inch) and how long before they make about 300mm (1 ft)?

Jaguars take about 5 or so months to hit about 6" depending on there diet. It would take about 15 months or so for it to hit about 1ft.
Best way to tell you is, they hit 10" very fast then slow down alot, it takes about 2-3 years for it to be about 15"