The triggered ability can trigger only once each turn. It doesn't matter whether Bard the Bowman was on the battlefield when the first card was drawn. If he's not on the battlefield when the second card is drawn, the ability can't trigger at all that turn. It won't trigger when the third or fourth card is drawn.

If you draw your second card in a turn while recruiting, the Human Soldier you create can be chosen as the target of Bard the Bowman's ability.