when will they lay, and why do they refuse veggies??

What pretty pullets!  Are they Orpingtons?  My hens started laying between 5 to 8 months of age depending on breed.  The hatchery BA and RIR started right about at 20 weeks. The BO hens started between 6-7 months.  One of my SS started at 8 months.  What I have noticed with my flock is that the hens that start laying later grow much bigger than hens of the same breed that started laying younger.

Generally I have to put new veggies in their run a few times before they figure out that the new green things will not kill them.  That said none of my chickens are interested in anything in the carrot-celery-parsley family.

My gals are also very disapionted when I give them veggies.  They run over happily, then give me a disapionted look like "we thought you had treats?" when I throw them lettus, carrots, zuccini, peas, weeds from the garden...

I trick mine into eating vegies when they're little, I grate whatever vegie I want them to eat into porridge and zap it in the microwave. They peck because they want the oats, the oats are sticky and stick to the grated vegie so it kind of forces the chick to try it! After a while they get chunks in porridge, now they're eat whatever I throw at them! Bonus is that the younger birds tend to copy so I don't have to bother over and over again!

Perhaps they feel they get enough in your yard We have no grass or weeds here except twice a year for a very short time so anything green gets our girls excited...well...except green bell peppers, they will not eat them.

This is basically what I do, at any age.  Scrambled eggs have worked great as a way to get them to try something new, though I have used cooked and raw oatmeal as well.  I just scramble the eggs then stir in whatever I have. 

With watermelon, they were hesitant but liked the seeds and I think discovered by accident that the fruit was good, too.  Apple trimmings even took some masking at first but now are a favorite.  I threw out a bag of frozen green beans for them that had gotten freezer burned one day and they wouldn't touch them -- but later that day there wasn't a green bean anywhere.  This week they are getting spent tomato plants.  Took them hours to eat the fruit from the first one.  Now they are stripped clean in a few minutes.