follow the linked recipe above - - you can get all the ingredients at whole foods - - and all are organic.
once mixed you can grind them up in a blender, if you choose, for the first few days. if you grind (it will look like sand kind of, no large chunks of anything), no grit is necessary. if you don't grind, or when you stop grinding, grit needs to be provided free choice.
if you follow the recipe above, it is important you include the kelp (you can get organic granules at whole foods from a company called 'maine coast') and the eggs. also, equally important, sprinkle a bit of brewers yeast on the eggs after you mash them up. brewers yeast is one of the few options you have for your vit Bs. use it. you can also get it at whole foods in the section where they have the vitamins and such. just to make you feel warm and fuzzy, brewers yeast is commonly used in organic feeds you buy from a store. use it with the above linked recipe.
just to clarify a statement from above, if you're following the standard of organic, you cannot feed them just anything for the first few days. the standard of organic calls for the bird to be in your possession from day 2 of life onward and only eating organic food. the reason for the 'day 2' part is that baby chicks do not eat the first day (and, in my experience, they rarely eat the second day, but that is what the standard calls for). once a chicken, on any day of its life, has eaten non-organic food, it cannot be consider part of the standard. there are no exceptions to that. they're strict. and for good reason. this may not apply to your goal, but wanted to clarify.
enjoy your chickens - - you're going to have a blast!
i bid you a great evening.
edited to add:
i forgot. when you mash up the eggs, mash them up with the egg shell. it offers a bit of grit as well as calcium and such. also, offer grit when feeding the eggs. i usually put some in with the eggs. and then offer some free choice, as well.