It's pretty quick.. You will need to have some money on the SIM to get it to work though. They will call the phone to confirm it's you... then on over at Google, they will call the T-Mobile SIM number as well, you enter a number or two, then done. Took me 3 days total, but maybe because it was a weekend.
Ooma is giving excuses to release my number. First time request was rejected by simple reason - Information does not match their records. I had to call t-mobile and verified Name/address again and will see how it goes. Not happy with transfer out being rejected.