How long can it take a hen to start laying?

[lengel]

My black sex links seem to be taking their time. What's the latest that they can start to lay?

Edited to say: Maybe I messed up their diet? They are in a chicken tractor eating hay in a field but I started supplementing with layer feed when they were about 14 weeks. When I say supplementing I mean that the food was available but they didn't eat much of it. Would this mess them up? Can I correct it?

 

[cmom]

Pullets shouldn't get layer feed until they start laying. The latest so far for one of my girls was 27 weeks, but I have heard of some that didn't start until 30 weeks. My first was 17 weeks.