Is there any chance to call me for interview before Oct-1?

USA H1B Visa
1

I gave start date as Nov 5th 2012, by chance if I called for interview before oct 1st, what will be the petition start date USCIS will give? Whether it will wil the date which I have given or oct 1st itself?

2

For H1B petitions, USCIS usually approves the requested start date as validity start date (USCIS will reject petitions with requested start date prior to 1st October 2012 for FY2013 quota).

I did not understand "if I called for interview before oct 1st". Could you be more specific?
3

Thanks Sujith. My petition start date is Nov 5th 2012. If USCIS called me for visa interview let say during Aug 2012, what will be the validity start date.
Is it Oct 1st 2012 or the date which I have given (Nov 5th).

4

I presume you meant stamping H1B VISA on your Passport:
As far as I know, USCIS do not do VISA stamping processes - all VISAs are usually processed by US consulates. You need to make an appointment with your nearest consulate in your Home country for VISA interview. Validity of stamped VISA determines when you can enter US, not when you can start work.
Your work start and end dates are as per the petition validity dates. If your I-797 notice says Nov 5th as the start date, its the date when you can start working on H1B status (but you may enter US 10 days prior to the work start date on stamped H1B).