The initial position is a draw. White is a tempo up, but that does not tip the scale. Black is OK. Black however has a narrower choice of good moves than white has. White can afford to lose 1 or 2 tempi as white is a tempo ahead. When black loses 1 or 2 tempi he might lose.
If after 12 moves you have lost no pieces or pawns, your king is safe, your pieces are developed into play, you control a fair share of the center, you have no structural weakness, then you have maintained equality.
Equalize
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Books recommend that, if playing as black, the first thing to do is to equalize in the opening. How do you know, after 12 moves and no pieces or pawns are lost, that you have equalized?