blochchain confirmations

[refta]

i have used instawallet to make transactions and at most after 20minutes i can have access to my coins. but since instawallet is down so i moved to blockchain.info. although i havent tried sending any coins yet but the coins i received from the took hours before they were confirmed. what i really want to clarify here is must i wait till full confirmations on blockchain before i can send or use my coins?