Starting from the initial position, the minimum moves you need to develop your game completely are:-
- 2 Pawn moves to let the Bishops out
- 4 Minor piece moves
- 1 Queen move
- 2 Rook moves, developed to a center file
- 1 King move, usually by castling, more often by O-O than by O-O-O
That makes a total of 10 developing moves. This holds for both sides, whether you're playing White or Black. Looking at it another way, you start the game with eight pieces. On their original squares the pieces are undeveloped. You need to make at least one move with each piece plus two Pawn moves for the Bishops. That makes ten moves.
See the diagram below for an example. Both players have made four moves : 1.e4 e5 2.Nc3 Nf6 3.Bc4 Nc6 4.d3 Bb4. White has developed two pieces, while Black has developed three. Does this mean that Black is leading in development? No, White has made two Pawn moves to let the Bishops out, Black has made only one.
White has used the first four moves to make the two required Pawn moves and two piece moves. Black has made one Pawn and three piece moves. The two players are neck and neck in the race to develop their pieces.
[The position in the diagram is from an opening called the Vienna Game.]
