In your game its 1.a3 Ba6(counter attack) gives the solution , therefore you can start making your decisions with one move deep, after playing many games you'll gain enough experience then start looking 2 moves deep for captures, checks and attacks and it goes on depending on your ability to calculate and the time remaining in the clock. With respect to your game - from my experience whenever our Knight is not present in the b1 Square I'll automatically play c3 (I won't consider a3).
Yes, I know all that, but the question is HOW MANY MOVES. People are not replying with the number of moves.
In your game its 1.a3 Ba6(counter attack) gives the solution , therefore you can start making your decisions with one move deep, after playing many games you'll gain enough experience then start looking 2 moves deep for captures, checks and attacks and it goes on depending on your ability to calculate and the time remaining in the clock. With respect to your game - from my experience whenever our Knight is not present in the b1 Square I'll automatically play c3 (I won't consider a3).