a turnover is a 6" triangle so cutting your fabric into 6" squares and cutting these in half diagonally should create the turnovers you are looking for.
info contained on
this website.
"...Turnovers - Hot out of the oven, Turnovers are 40, 6-inch squares cut in half diagonally to yield 80 half square triangles."
here is a really tip helpful
site and they have a precut guide downloaded chart at 9.201