Your employer will need to file for an H-1B at the beginning of April 2013. You will then have to apply for an H-1B visa stamp in late September 2013, and would then enter the US no earlier than September 20, 2013 with that visa stamp.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.