I have 3 hens and 1 rooster who are now 14.5 weeks old. I have about 2 weeks worth of pullet grower feed left. This would put them around 16.5 weeks. Is that too early to transition to layer pellets? My farmer supply store only sells the large bags of feed, so if I buy more grower, I will have leftovers. Could I keep mixing in the leftover grower, even after 18-20 weeks when they start laying? Or should they strictly be on layer food only (once they start laying)? I'm not being cheap as I don't mind buying more grower feed, it's just that I will only need it for 2-3 weeks and it seems a shame to waste the leftovers?