Question regarding I94

Hi Guys,

My H1B Visa & I94 expires on 30th Sep 2015. I am planning to change my visa status to H4.

My questions are below…

1.How long will it take to COS to H4?

  1. If I don’t get the approval before Sep 30th Can I stay in US with the COS receipt or I should leave?

Thanks in Advance,