I normally put 3-4 layers on at the same time. I know some people wait between layers but I tried it and did not see a difference, except I had a separation between layers one time when I waited.
I would say just keep going, try to keep it smooth and even and lay them like bricks, overlapping. On the last layer pay special attention to the surface your leaving, you can do some minor sanding to sinew but not really recommended because it compromises the fiber backing. I almost always cover sinew with snake skin (because I don't like the way sinew looks) and it covers the imperfections. I'm getting ready to do another right now using TBIII for the first time. I usually use hide glue. Keep us posted.
Mark