Questions about feed for 12 wk old cockerels?

[BWchicken]

I have two 12 week old bantam cockerels, and no pullets (yet). They have been on 18% starter/grower medicated crumbles, and it's time to get a new bag. I'm thinking of getting Dumor 20% grower unmedicated. Wouldn't the higher protein be better for them than the 18% they've been getting?

Also, at what age do I take them off the grower and what kind of feed should they get after that?

Thanks!