there are several "levels" of organic really, depending on what you want to accomplish.
if you are only talking egg production, then hens
could eat regular food until they started laying, and then you would need to switch to organic, but it's best to start organic from day one. since you probably aren't trying to make a big business out of this, you can sell some eggs as organic without being certified (check locally for specific #s as it is different everywhere). you need to clearly state that you are not certified organic, but that you feed organic. certification is expensive and most people will understand that. also, you need to try to avoid medications such as chemical dewormer and antibiotics. if you HAVE to use them, make sure to find out how long the medication is in their system and discard all eggs you collect from them until that time is up.
if you are talking meat production, those birds need to be fed organic from day one. some vaccinations are allowable, such as Marek's and cocci, but medicated feed isn't. absolutely no medications other than vaccinations are allowed for organic meat. if a bird gets sick and needs to be treated chemically and there isn't an organic alternative, do it. being organic doesn't mean neglecting the health of your birds. process it with the rest of your birds and sell it as "natural" instead of "organic" (this will require very good records and identification of your birds because you really can't mess this up) or sell the bird to someone who raises non-organic.
most importantly, learn as much as you can about poultry nutrition. there are some great sites on my BYC page for getting you started. the more you know about poultry nutrition, the better quality feeds you will find, and the better your organic business with thrive! you also need to learn about poultry illnesses and alternative treatments. BYC and the sister site
SufficientSelf (look under
this thread) are great resources for alternative treatments.
lastly, be proud of yourself! most 14 year olds don't even know or care where their food comes from and here you are, already thinking about organics! it's very impressive. you, young man, are the future!