I started trying this with Windows 8 a few days ago and the computer was still at about 50% for about 21 hours......on a 100mbs internet connection.
16gb Sandisk USB stick. Tried it 2 days ago with a 64gb stick with the same results.
This is a late 2012 rMBP. With the latest Mountain Lion updates.
Tried it yesterday with an 8GB stick. NOGO.
Trying it again with a 15GB stick. It is still stuck at 50% for the last 3 hours.
What can I be doing wrong?
Apple support told me to go WIRED and that would normally work when wireless keeps hanging.
So, I did. And, 30 minutes later, I am still looking at a 50% blue bar.