In MetaTrader terminals, commission is charged after the trade is closed. This means that once the position is closed, the commission amount is visible in the "History" tab (or "Account History" in MT4) under the "Commission" column.
The commission amount for the minimum trading volume is indicated in the Instrument Specifications and is reflected in the final result of the trade.
This method helps reduce the initial margin load on your account, which is especially useful when opening multiple positions simultaneously.