I am currently working with company XX. They have started my regular H1B processing for October 1st 2011 as the start date.My LCA Application was approved a week before.They have filed my H1 petition with USCIS on July 1st 2011. I am currently on F1-OPT visa which is valid until Jan 02nd 2012.

1. How long would it take for the H1B to get approved?

2. Is it possible to switch company YY before getting the H1B approval with the current company XX(when the petition is in process)?

3. When is the earliest I can switch to company YY? If its not possible to switch company before the approval, Can I switch company after H1B approval but before getting the visa stamp? (or should I go out of the country, get the stamping and then come back and try to switch).