H1B Visa Stamping

[Diamond19]

Hello,

My H1 B visa is valid til mid of April 2013 and i plan to visit India in December 2012.

I received my H1B visa in this US while i was in H4 and this will be my first trip out of this country ever since i received H1B visa Petition so i also need to go for visa stamping in India.

Question:

1. If i start process of my Visa extension in October 2012, can i leave US?

2. And if i don't start Visa Extension, Is it risky to go for stamping in December while there will be only 3-3.5 months left in Visa validatiy.

Please suggest.

Thanks,