What i did is when the starter was almost gone and they were almost 15 weeks old, i just started them on Layena Purina. So if you are running out of their starter and they are 15 or 16 weeks old you can get them started on layer cumbles. If not keep them on the starter.
chicks got to 17 wks needed feed talked to the feed store since I needed feed they said it wouldn't hurt to go ahead and get layer at that age. I did not seem to hurt them they started laying at 18 1/2 weeks and haven't let up.
I went to our local feed store to get some starter or grower food. They had starter and layer and that was all. I asked them when to swtch and their answer was that I should feed layer from the time they are hatched!! I chose not to take this advice.
Yes, you will get a lot of different answers on what to feed them and when. I think part of that is that there are a lot of different choices and some feed stores don't carry all the options. And not all feed store employees know what they are talking about. I base my decisions on this site.
Thank you,Ridgerunner, for that link to feeding chickens ,it clears up the time to switch etc. I feel like printing it for the feed store! Our store is good -if you get the right person. It would save them time too.