L1B visa to H1B visa conversion with COS

I had H1B petition that was not stamped and was valid from Aug 2008-Aug 2011. I did not travelled during that time hence my petition was not stamped. After that my company applied for L1B visa in Sept 2011 and it was stamped (valid from Sep 2011 to Sep 2014).

Currently I am in L1B visa working in USA with Company A and my L1B Visa has a validity till Sep 2014 and I have got the I94 date till Oct 2016. I don’t want to quit my Company A in next 1 year or so, my question is that can I apply for H1B visa when I am in I94, what is the COS ? Does it apply for me considering I had H1B petition & valid L1B visa could you please explain on this. Can I do a COS at any time or I have to wait till the April 1 for the H1B visa cap.