Do it at once, first tru to mix 2 colours on the paper, see how it workrs, regulate level of wetness of the paper/ Than go on. Watercolour doesnt like mixture of more than 3 colours at once - colour became dirty(But I do it sometimes carefully)) You can do it again as the second layer after your first layer will dry, but also try do it in not more that 3 layer or picture will loose its transparency/
You are very brave using so many colors! A lot of artists are afraid of color (I don't know why), and you just stand out among them with this.
Great job on the editing. You didn't fill the whole thing in and the open space around it really makes it so much stronger. The looseness of it all, and splatters, really make the feeling of wild and free very powerful.