I think the transaction usually happens instantly, it just takes a while for blockchain to confirm it. Although I've experienced transactions where I've sent from 1 wallet to another and it did take 1 or 2 hours. That was my first withdraw with btc, I thought I did something wrong, LOL.
It happens same for me, it shows me unconfirmed at first, however as minutes click I got the messages shows the confirmed, usually this process takes me more or less 5 - 6 minutes. But everything is safe and secured, for those minutes I was bit scared LOL...