Hella fast. Depends on the temp, tank size, and amount of food. Since they are one of the top predators, and as juv. they are easy prey, they probably have to grow as fast as possible. I'd put them between silver arowana, pbass, and crenicichla for growth. Crazy fast. Expect at least a foot in the first year.
How much for second day priority? Fedex, UPS, or USPS?