Depends on how much you feed them and water temp. I have a spawn right now that have been free swimming for a week that are almost 1/4 inch. I feed hikari first bites and brine shrimp 3 times a day and of course they get tiny bits of their parents nls pellets.
It should reach one inch in about 3 weeks, but could still be that size in three months. Maybe an inch every two months with great feeding, water changes, etc..
i gave some fry to a friend of mine and had them to about 2 " in a couple months. Mine which i ignored and just let eat algae and left overs were still about 1/4-3/8".
ofcourse i also have a female which Ive had for almost a year now that is nearly the same size as when i got her. even being in a 220 and not breeding
pretty slow during winter, my fry are 5 months old and all different sizes (1/2 inch to 1 1/2 inchs), it seems now they are all doing a growth spurt with the longer daylight hours