I agree with ShellyBorg. Hand-feeding a baby bird is a lot of work.
You have to sterilize all your equipment (spoon/syringe etc) and also keep yourself 100% clean.
The temperature of the hand-rearing formula MUST be perfect.
You will most likely have to get up in the middle of the night to feed the bird.
You have to keep it in a warm room/exceptional incubator, and the temperatures MUST be right.
If you are not an experienced hand-feeder, it can be all too easy to actually kill your bird by hand-feeding improperly. Some of the food can go down the wrong way, it can suffocate, so many issues can arise from hand-feeding. Even with experienced hand-raisers problems can arise.
I would not recommend hand-feeding a bird yourself unless you have good experience.
I never add anything to the hand-rearing formulas i use/used (Kaytee Exact or Vetafarm Neocare). Unless a particular bird is in dire need of an addition.
Also, with formula, the water/formula mix needs to be perfect. Not enough water can cause the formula to become like cement in the birds crop (which causes many many life-threatening issues), if you have too much water, the bird won't get the nutrients it needs, and may develop diarrhoea.
I cannot stress to you enough just how much can go wrong. Not trying to scare you or be mean at all. I just feel very strongly about hand-raising birds if you don't know what you're doing. ^^
Also, cuttlebones/millet sprays can be given at any age really. I give my parrots millet sprays etc. around 4-5 weeks old so they can nibble and play with it. They eventually learn, "Oh hey! I can EAT this!! :O"
~Kinny