I got this information from my herbalist when my son was starting solids. I went to their website and it hasn't changed since. I didn't follow this exactly, but I think it's a good list. Their website is:
http://www.gaiagarden.com

SUGGESTED TIMETABLE FOR INTRODUCTION OF FOOD ITEMS:

6 months:
Cherries (remove stones)
Banana
Blackberries
Applesauce
Seedless grapes (smashed)
Pears
Blueberries
Carrot (cooked and smashed)
Sprouts (blended with water) *I would blend with EBM*
Yams (cooked and smashed)
Beets (cooked and smashed)

9 months:
Papaya
Nectarine
Apples
Mashed potato
Artichoke
Cabbage
Broccoli
Peas
Green
beans
Oatmeal
Rice
Millet

12 months:
Squash
Asparagus
Avocado
Chard
Parsnips
Onions
Garlic
Tofu
Barley
Blackstrap molasses
Goats milk

18 months:
Chickpea flour (pancakes, muffins etc)
Greens (lettuce, beet greens etc)
Eggplant
Buckwheat
Rye
Kelp
Tahini
Cooked beans/legumes
Fish

21 months:
Oranges
Wheat
Pineapple
Brewers yeast
Cashew or almond butter
Eggs
Meats

2 years:
Sunflower, pumpkin and sesame seeds
Peanut butter
Corn