The only thing I can think of is to layit out on a piece of paper. You wouldn't have to necessarily draw it but just put R/W/B on the paper. Your first row could be R/W/B/R/W/B/R/W/B, 2nd could be W/B/R/W/B/R/W/B/R, etc. If you are using a pattern you could just copy the pattern (B&W) and write directly on it.
I do have a design wall, but if working with a certain number of colors I have done as described above.