Restrict feed on bbws?

[WIchickens]

I have 28 BBWs that are almost 3 weeks old. I am supposed to start restricting feed, like the Cornish X, 12 hours on and 12 hours off? Or can they handle free choice?

 

[GitaBooks]

I would probably restrict feeding like with the Cornish Crosses, so they don't develop leg problems.