I have used new borns and just cut a place for the tail to come out seem to work great and so much cheaper to.
I do the same thing. Used the newborn size. Sometimes I have a little trouble cutting the hole at the proper spot. I have also learned to do the cutting over a waste basket as the little absorbant granules spill out when cutting. The diapers have worked much better than the panties that are sold and no laundring involved.