I have been working on H1B visa for over 4 y, how long do I have to apply for green card, how long does it tak

Answer 1

You do not apply, Your US company must be willing to sponsor you for the green card. I know a few people waiting for their green cards through a H1B visa. One couple has started the process in Nov 2001 and will get their green cards by summer 2008 and the other couple will have theirs in a few more years they applied for their green cards through a H1B in 2003.

The backlog for the green card is about 6 years

Answer 2

Nobody knows how long it will take to actually obtain green card. There is tremendous backlog in employment based green card process. If your employee is willing to sponsor your green card, it is Multi step process until you actually apply for the adjustment of status. Your employer should start filing for the approval of Labor Certification (LC) with Department of State. And then your employer will file the form I-140 Petition for Alien worker. After your visa number becomes current, your employer then file the form I-485 the Adjustment of Status with the approvals of the I-140 approval and LC.
For more information at the forum of www.immigrationvoice.org. This is the website is for the employment based immigrants who are skilled workers. You will find many valuable information there. Good luck!