Your H4 status is derived from your spouse's H1B status. Your H4 status is not an employer specific visa status. You can apply for H1B now, but if you then extend H4 status after applying for H1B, then it might not be clear to USCIS which status you want to change to. According to Last Action Rule, your status might be the last status granted by USCIS, not the status of your choice.
You should plan ahead with your attorney.
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The H-4 to H-1B stand's on its own, but its going to be an isue of first in first out. I would apply for the H-4 to H-1B COS under premium processing while your current H-4 is still valid since the wait now either for a COS or EOS unless paid for under premium processing takes about 4-5 months. Therefore, instead of confusing USCIS, I would apply for the H-4 porting COS application from your husband and then come April 1, 2013, apply for COS from H-4 to H-1B premium to preempt the H-4 EOS. Good luck.
I agree with my colleague Mr. Calehr. You should consult an experienced immigration attorney for this matter. You may schedule a consultation with an immigration lawyer in your area, my firm is handling these matters in New York. If you would like free legal updates on these immigration issues you may sign up for our newsletter at http://www.shautsova.com .
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