Generally doing the labor certification isn't hard, just time consuming and a lot of paperwork. 1-2 years is not uncommon even with the new PERM system. After that it depends what country you come from.
The main gotcha is you cannot use your experience of doing the position on your H-1B towards your labor certification application if you are currently employed in the position so you'll have go on your previous experience.
As ever consult a lawyer. This goes double for immigration related stuff.
After your PERM is approved, you get to file for I-140, which takes another 4-6 months. Then you get to wait until your priority date becomes current which depends on your category and country of origin. This could be anywhere from immediate to 10+ years.
Once your PD is current, you get to apply for I-485 which takes anywhere from 2-6 months and includes doctors exams, finger printing and possible interviews by USCIS. Of course while they're processing this there is no guarantee they wont retrogress your priority date and put you back into the waiting game.
Of course all of this starts again if you change employers (but you do get to keep your priority date if you had an approved I-140).
But, I don't do any state of the art research, or highly specialized academic work, or anything worth publishing on academic journals.
How hard is to do the Labor Certification for the EB-2 green card?
Edit:grammar