No, you cannot work until October 1, 2011 even if the petition is approved before October 1, 2011. Because you are on a visitor's visa, which is not work authorized, you cannot work until the new H-1b fiscal year begins on October 1, 2011. Working illegally before then will cause your petition to be revoked. Only international students on F-1 visa who receives Optional Practical Training (OPT) can work as soon as the petition is approved because OPT is a work authorized status. Your visit visa status is NOT work authorized and therefore you have to wait until October 1, 2011. USCIS will begin accepting H1b petition in the beginning of April, but the H-1b fiscal year starts on October 1, 2011. The law allows H1b filing with USCIS 6 month before the beginning of the H-1b fiscal year (hence April submission).
Answered on Jan 31st, 2011 at 9:13 AM