Going to echo what GrowCN has said here... except to caution you not to overwater the plants... overwatering is the state of being constantly wet so no matter how much water you use, just make sure it dries out between waterings.
I'll also echo him with your homemade fertilizer... I can't see the benefit ... distilled water has ZERO anything in it.. H2O2 is good for adding aeration to the soil but provides no nutrients... and your plain tap water obviously has something in it since you say it's "fine" in terms of ppm - but what constitutes that ppm - and how do you increase it as the plant, when it grows, needs more and more of different nutrients? So that leaves us with your onion skins... Onion peels have a good amount of plant nutrients like nitrogen, phosphorus, potassium, calcium, iron, magnesium and copper - but do you know how much of each? How would you adjust to the needs of a growing plant? How would you reduce, for example, the nitrogen and increase the phosphorous and potassium if needed?
For my money, I'd buy some organic nutes where all that guess work has been done for you and you can confidently feed and nuture your grow ... unless you really are a chemist and have a means of measuring the relative NPK composition of your onion peels...
Good luck!