When hammering the ledger ensure that you do a thorough job of securing the ledger compactly i e.
How to frame a soffit roof.
It is better that you use steel coated nails or any other variety of roofing nails recommended by a hardware store.
Measure and mark that distance in at the end of the wall.
To find the long points for the lower plate of the dropped gable set a square to 5 inches 3 1 2 inches for the lookouts and 1 1 2 inches for the top plate.
Slide the square down the rafter and mark where it touches the top of the wall.
Hammer it hard to avoid any spacing.