You can feed medicated all the way to point of lay. Typically you stop when the bag runs out minimum of 8 weeks old but guess you'll have to keep them on it. Don't worry, they'll start eating a lot more feed once they get older and it will go quickly. Might even be old enough to change over to pellet feed by the time you go through two bags of starter. I find much less feed waste using pellets with large birds. They through the crumbles on the floor and then wont eat it when full grown. A turkey finisher or all flock type feed will come in pellet form and not have the high calcium that layer feed does.
