As fas as I know, people who have applied under EB2 are getting it in anywhere between 10 months and 20 months if they are with industries or companies, slightly quicker if they have higher degrees and are with government services or universities. EB3 will take anywhere between three and four years. I am not a lawyer/lier but I know enough Nepalese who have recently got gc through these two categories around here in Chicago and Boston. If you have a Master's and apply under EB2, it's good. If you have a Ph.D. and some grants/awards+publications, you may qualify for EB1 in which case you get your gc in 2-3 months as an outstanding researcher/professor.
Clarification: The time noted above is after your labor certification for EB2 and 3.
Hope this helps.
Best,
simon