How long will it take for an Indian to get EB2 with NIW after we apply? Because, I heard that EB1-A or B takes only 6-7 month even for Indians and Chinese.
There are two steps to getting a green card: filing an I-140 to qualify yourself under certain immigration category (such as EB-2 NIW) and filing an I-485 to adjust your immigration status. It takes the USCIS on average 2-6 months to process I-140 petitions. For more information regarding current processing times, please see this link.
Since you were born in India, your priority date is not current for EB-2 categories. So, you will need to wait until your priority date is current before you will be eligible to file the I-485 for adjustment of status. The priority date for people born in India with approved EB-2 petitions is currently November 15, 2004. But, it is hard to say how long you will need to wait for your priority date to become current, as priority dates do fluctuate. For example, in Feburary 2012, the priority date for people born in India under EB-2 was 2010.
One advantage to filing under EB-2 NIW is that if your I-140 remains pending for at least 365 days and you have an H-1B visa, your employer can extend your H-1B status for one year at a time beyond the normal 6-year maximum in H-1B status. Once your I-140 has been approved, and if your country is still backlogged so you cannot file your I-485, your employer can extend your H-1B status for up to 3 years.