Ok, I was reading Aimees thread in the general section, but didnt want to hijack her thread. My ladies are 16 1/2 - 17 wks old now and my question is....would it be all right to make the switch from starter to layer now, or wait till they are 18 wks? And when i do make it should it be done over a period of a week or so or all at once? Also, oyster shell after first egg...correct? THANKS!