My "ladies" are now starting their 15th week. After all my reading they should go to "laying "food around 18 weeks. I have about 20# of there starer/grower food which contains 18 protein left. Can I finish that first, mix it together with new food or just start with the new layer food in a few weeks?? I also give them gravel with there small treat of human food. Do i still need to do that? Thanks for the help