exchange status B2-F1 pending, how long?

[mermaid22]

Hello!
The college sent my documents to exchange visa status from B2 to F1. They sent it 2 weeks before my I-94 was expired (March 24). I got receipt from USCIS March 12.

Who already did that same, how long does it takes to waite an answer about approval or refuse?

In July 24 my grace period will ended, and If I get no answer, may I leave USA?

I do not want lost my multy visa B2. And how can i be sure that it was not canseled?

Thank you!

[orion]

First, it was a bad idea to do a COS from B2 to F1. Ideally, you should have applied for it from your home country. If it takes too long for a decision then you lose your B2 as well. And if you do, you can know about it at the PoE when you try to visit again. USCIS may or may not be able to tell. The website will tell you current application processing dates.

[mermaid22]

First, it was a bad idea to do a COS from B2 to F1. Ideally, you should have applied for it from your home country. If it takes too long for a decision then you lose your B2 as well. And if you do, you can know about it at the PoE when you try to visit again. USCIS may or may not be able to tell. The website will tell you current application processing dates.

Thank you for answer, but now I know that it was bad idea.
I have been on web site of USCIS and I have seen the current application processing dates for Vermont center, where my case is pending. It looks like they work with cases from August 2007! But some people told me that takes about 3-4 month. So, what should I do now to save my B-2 visa? What happened if I leave USA before answer from USCIS? I know they canseled my application, but what about my B-2? How can I know that it still valid?
Thank you!