I try to avoid seaming in the bias binding....so i would make the strips as long as i could given the fabric i was using...and follow Tartan's advice....shorter pieces where the ends can be hidden as the pattern passes under another strip.
Good luck....i have seen a few Celtic knot quilts and they can be so stunning. I have a copy of the Book of Kells - and i spend time looking at the pictures and dreaming about the quilt i'd like to make some day.