H1 stay & Cool off period defination

I have completed 4 years, 5 months with L1 Legal Stay in USA. Moved back to India in December 2014.
My question is, If i have a fresh H1 this year, cleared lottery and waiting for petition approval, will it be eligible for full 6years term ?, if i travel post December 2015 instead of OCtober 2015 Or, would I only be able to apply for rest 1 year 7 months as I have spent close to 4 years and 5 months in L1 already?

I think my question specifically is on how the cool off period(1 year) is defined: is it just the time I remain outside the USA before I enter again, or the duration from the time when I left the USA (in december 2014) and the time when I will apply my petition (April 2015)? …

Its the time you stayed out side US. In your case if you stay out till December 2015 your clock will be reset and you will get a full 6 year term. But while adjudicating your case you might get visa validity till 1 year 7 month starting from 1st October 2015. But as I said if you come here after December 2015 then you can file for extension and ask for 3 years extension. Its best to let the clock reset.