I'd really like to to exchange BTC for XMR. I'm attempting a transaction via Circle.com to ShapeShift.io according to this guide:
https://forum.getmonero.org/5/support/2384/the-easiest-way-to-buy-monero
Circle is currently taking hours to process, only to inform me that it fails. I've only ever exchanged USD to BTC before, so this is my first time exchanging BTC for another currency.
Being unable to find simple, straightforward exchange is a barrier to using these currencies. I'm not looking to be a trader. I just want to exchange BTC for XMR the easiest way possible. I don't know why the exchange from Circle to ShapeShift is failing, but I need something that works.
Is there some alternative method to easily exchange BTC to Monero?
Update: While the selected answer is correct regarding the time limits, this problem is directly related to Circle dot com failing to complete BTC transactions. I have not been able to access my funds since creating an account with them. As for the Monero guide linked to here, I highly recommend using another option if you need to purchase BTC before exchanging for XMR.
Update II: The delays were entirely due to account verification being incomplete. I have since tested and precise ShapeShift transfers are successful and quick.