I have about a 1/4 of a bag of starter left and did not want to buy more since the girls are 19 weeks old and should be close to laying. So I bought a bag of layena. Can I just mix the rest of the starter in with the Layena and start feeding them that? OR do I need to wait til I see an egg to switch them? I raise dogs and I know that when you switch feed you should mix the new with the old so their tummies get used to it, was not sure if this is the same with chickens. Thought/Advise?