I also use Niagra spray starch-non aerosol-save the empty bottle, then mixed up the Sta-flo starch. I think I used either 2:1 or 3:1 . If you soak the fabrics, you will be wasting a lot of starch besides being messier and time consuming.
You have to iron fabrics anyway, so find a time with favorite show (mine is Kathy Lee and Hoda) set ironing board in front of tv under ceiling fan and iron away with spray starch. I iron backs and other yardage this way-then cut and sew.
Just MHO.