H1 transfer (with I-140 approved in Jan 2012)

[MVG]

I am in 5th year of H1B, My I-140 with current employer was approved in Jan 2012. I have the copy of I-140 approval notice.

If I join new employer (Full time or Consulting), will my H1 transfer give me 3 years of H1 OR only upto end of 6th year? Is there any law that I must wait until I-140 is 6 months old in order to get 3 years H1 when I transfer H1 to new employer?

I am not willing to change job if it does not give me 3 years of H1. If so, I will wait until I-140 is 6 months old.

Thanks for all your help.