I use a 11 x14 devere with colour head and my starting point is always 0 magenta and 0 yellow, I will go to a different filter when needed due to what Owen says.
Originally Posted by Oren Grad
You won't save yourself trouble. The grade numbers on the filters are arbitrary; the actual contrast you get in your prints is affected by a number of other factors as well, including light source, paper and developer. If you change your enlarger head you could well end up with different behavior, just as if you change paper or developer. It's possible to be more precise about this by making careful sensitometric measurements - get a copy of Phil Davis's "Beyond the Zone System" if you're interested in learning more. But you don't need to if everything is working fine for you.
FWIW, I use an LPL 4500II with color head. I dial in yellow or magenta filtration as needed by the particular negative + paper combination I'm using. If the negative doesn't need any filtration, then I print without any filtration.