@Seriousnepali, He is not that desperate to have GC right now but he would love to have work authorization card. At this moment he doesn't yet have SSN but he is maintaining his F1 status in good condition. His wife is permanent resident only since last six months so, it will take her around 5 years to be citizen.

@pshrestha78, @riddle and @ Seriousnepali, thank you guys for your valuable information on this matter.

from your and what i have googled so far, I came to the conclusion that it is right time to file I-130 for my friend.

if any of you have additional experience and information on this matter, your inputs are always welcome.

Thanks again.

One more thing, do my friend have to hire an immigration lawyer to file I-130 for him or Can he do it himself? what do you suggest?