Some laying some not

[Chickenmama1614]

Ok so my question still remains. I currently have all 16 week chickens. All are still on chick starter. Received my first egg this morning. Do I start all of them on layer feed now? Just oyster shells? I have 12 that shouldn’t start laying til 20weeks of age.

 

[Birdsong 82]

The recommended I usually see is 18 weeks If they were 16 weeks and it was me a time for fresh bag I would go ahead and switch them