Whether you can safely add the water directly from your tap without aging it for at least 24 hours is going to depend on it's quality. You should test your tap water for ammonia, nitrates, nitrites, PH, KH & GH to know where you stand first. This way you will also know if your PH will be stable (crushed coral (increase ph) or peat moss (lower ph)) can make a difference as well.
Never just assume your tap water is safe to add directly to your tank without having all information on hand.
Never just assume your tap water is safe to add directly to your tank without having all information on hand.