I am sorry but that lady is.. Interesting.
I love my chickens, but they are CHICKENS. For however many years they have been born outside, and some might even think if they all don't make it, it was meant to be. Darwin's therory takes hold here.
When I had my first chicks, they were outside from day 1, and had the heat lamp on their insecure 'coop' whenever they got cold. Well surprise to me, they chose outside and fun rather then sitting at home under heat, even at 7-10 days old. Their mother would have to get off them and get water, food and so on.
It cracks me up these people who are SO vigilant with 'rules' that they don't realize Nature needs to take it's course, whether you are ready or not.
My advice? Bring them outside whenever the weather is nice. I think it takes a constant cold or chill to get them sick, but I am sure you will notice they are COLD and NOT HAPPY, or otherwise. It will also build them up for going out full time so you don't shock them from inside heat light to big scary outdoors.
Hope I didn't come across as rude, I don't mean to be at ALL and I praise you for taking this lady's words with a grain of salt. You have a varity of experience here, but all is good. I doubt people on here would be doing harmful things to their chicks (like god forbid feeding treats lol).
I started introducing treats with chick grit at about 1-2 weeks old. Some things are better then others at different ages, I find my chicks LOVE raisins and raw oatmeal, but that's about the extent of their experimenting. They are PICKY lol