Like JanRN, I PPd the FWS, also the PC (which JanRN also did!). I press the block, as I do each seam, trimming the seams as necessary. For the outside pieces, I always extend them beyond the seam lines marked on the paper. After all the piecing is done, I remove all the papers, and press again, with a shot or two of Best Press. Then, I do the final trimming for the outside ragged pieces, and square up accordingly.
Like JanRN, all stays nice and firm and square by removing the paper as you go. Besides, I wouldn't want the long drawn out task of removing all the papers from the whole quilt. It isn't much of a job when doing it as you go.
I'll look forward to seeing all of your Kimonos together! It must have been a fun quilt to do.