L.,
I was in the same boat as you, not knowing what to do. We started our son out on Rice cereal, then oatmeal, then mixed cereal, then veggies. We started with the least sweet; green beans, then squash, carrots, sweet peas, finally sweet potatoes. We started new food on a sunday and went an entire week on that veggie before moving on, just to make sure he didn't have a reaction. Plus it was easier for me to remember.
Just remember your dr. is just giving you an idea of what to do, you are her momma and you know what is best for her. If you think you should start with cereal then go for it. Watching them eat baby food is so fun, I enjoy every minute of it.