L1 - H1 & as 5 year L1 stay completes, when does the clock reset and to apply for H1

[vrbanala]

Hello,
I have started working in March 2010 and I was out of USA for 12 months for 11 month stay in India once and 6 months for personal reasons in India.
I will be completing my stay in USA as l1 b visa holder for 5 years in June 2015. I will have to go back in June 2015 as L1 VISa expires.

Can I apply h1 b in April 2017 for stay upto 6 years(I heard that 3 year at a time and an extension after that)
or do I have to wait until April 2018?


Could you please help me understand.


Thanks
Venkat