Any order is allowed: that's the puzzle. Each lap is drawn over whatever went on before it, and the hose test checks the result the way rain does. Water runs down the wall, so every piece has to lap over the piece below it and tuck under the piece above it.

    House wrap (white), I-cut, head flap taped upSill flashing (amber), fasteners (red)Flashing tape (violet); wrap tape (blue)Sealant bead (brown); wet spots (dark blue)Flanged window in a wall that's already wrapped: sill flashing, sealant at the head and jambs, window, jamb flashing over the fins and over the sill flashing, head flashing over the jamb flashing, then the wrap's head flap down over the head flashing and its cuts taped. Colours are a code for the materials. Follow the window maker's and the wrap maker's instructions and your local code.