I had my best friend with the same issue two months ago, but then she decided to coat with a few layers of white paint and the mess was huge, had to pay for this cleaners because she was too lazy to remove the furniture and the carpets. But there is one thing I've learned from her - something she realized a weeks later, unfortunately. When you have to hide a dark color with a lighter one, the number of coats of paint needed has everything to do with the hiding power of the paint or the primer you use, and nothing to do with the color you paint over. The hiding power depends on how much pigments there are in the paint /the one with more titanium dioxide in the list of ingredients is what you're looking for/. If possible, choose a flat paint over a gloss one, it has a lot more pigments in the film volume. Earth tone pigments like brown, black, ocher and mustard yellow, hide much better than bright colors like bright yellow, forest green, blood red and navy blue. And therefore, expect to spend more - quality matters here.