Calibration Round #1

There is only one knight in an $8 \times 8$ chessboard. The knight is currently at the square of any of the four corners of the board. What is the least number of moves that will take the knight to go to the diagonally opposite square of the current one?

In any move, a knight first goes 2 squares upward/downward or right/left, then another square horizontally to the direction it first went.

Calibration Round #1