I start mine giving mostly veggies when they are just days old, by the time they are 8 to 9 weeks old they are used to eating different items and usually they will eat happily whatever I put down for them.
Chickens are defiantly NOT vegetarians and we should never try to make them. There bodies need meat protein for a variety of reasons and to keep them healthy give it to them. I do feed a vegetarian diet but I add meat protein to that everyday, making sure not to over do it as to cause them...
I have always given my birds some greens when I have it, after a lot of of reading today I gave them their first meal of eggs, a leftover waffle, flax meal and topped it off with a cheese burger man they went nuts over it..