DIY coloring can be forgiven when a sudden need or whim arises. However, generally speaking, coloring your hair is a definite no-no unless you happen to be a professional hairdresser or at least have professional knowledge to know exactly what you are doing.
In most likelihood, in the end you will anyway be forced to go to the salon, which will make it more costlier and even more harder to undo the haphazard damage you may have wreaked on your hair. So, do let a professional take over from the beginning itself.
Solution: Remember to fix up that hair color appointment with us!