Unless the H-1B is cap-exempt, it would be effective only on October 1st (assuming it is chosen in a potential lottery and approved). There would be a gap from August-October and you would need to have a valid status during this period or apply for a visa abroad. Discuss the specifics with an immigration attorney for more detailed advice.
Kindly note that this posting is offered for informational purposes only. It does not constitute an attorney-client relationship. Remember, this site is akin to an internet blog. Do not rely on information here to make important decisions in your life. Make an appointment to meet with a licensed attorney in his or her office (or via Skype or phone) to obtain competent personal and professional guidance.
Your H-1B if your employer is cap-subject will not permit you to start working until October 1, 2014. So you must either leave the US and return, or find a way to maintain your nonimmigrant status between August and October. Please see
Mr. Shusterman is a former INS Trial Attorney (1976-82) with over 35 years of immigration experience. His response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.