I've stated this before for someone, but it really doesn't matter, just do it well.
However, if you are worried about time, I highly suggest you build yourself a schedule and see if colour is even an option for you. It's important to stick with a schedule when you can, and if you think you won't be able to keep up with whatever timeline you have in mind, then I would probably lean more towards b&w.
But in the end its up to you. Colour or not, a comic can be very successful. Colour isn't what makes a comic attractive necessarily, and it certainly doesn't determine the quality of the story.
Just pick the option that works best for your schedule and feels right for your story.
Best of luck in your decision,
Wintre