The transaction is propagated through the network in a few seconds. The bitcoin wallet will allow you to spend the funds received, even if they are not confirme

The transaction is propagated through the network in a few seconds. The bitcoin wallet will allow you to spend the funds received, even if they are not confirmed by the network[1]. You simply add the risk of a double-spend attack against your balance, if an attacker also sent coins to someone else. It is up to miner discretion which transactions to include in blocks. If the fee included is zero, then many miners will pass on your transaction, and it may take longer to confirm the original transaction. [1] https://github.com/bitcoin/bitcoin/issues/3288#issuecomment-28923237 https://github.com/bitcoin/bitcoin/issues/3288#issuecomment-...