Thank you, both - for your answers.

Work-Shy, I should have clarified - my question was even though the email says confirmation within 24hrs, I wanted to know if, at times, confirmation comes earlier. I am really hoping the upgrade requests come through - and if not, then I need to start re-setting my expectations of spending 13hrs in economy

Thepingunicornshirtguy - Thanks! Exactly what I needed.