My girls are going on 13 weeks old, and we have about a week-and-a-half to two-weeks worth of food (starter) left. I'm wondering if I should go ahead and get a 50# bag of layer crumbles as their next food, or if I should get a 25# 'interim' bag of starter to get them a little bit older before switching them. I've heard that the switch can be made at about 16 weeks, but I don't think I have enough to hold them over that long. But I don't want to switch them too early and mess them up with too much calcium. I considered keeping them on starter till they finish up one more 50# bag, but by then they will probably be between 18 & 20 weeks old (their feed consumption dropped when we got rid of the roos) and some of them might be starting to lay by then (I hope). What do y'all suggest?