Labor Certification Substitution ended on 07/16/2007

So you are a lucky one.
Since there is no more premium processing for I-140, it takes any where from 6 months to 1 year before I-140 is approved.
Besides, DOL and USCIS do frown upon the practice of labor certification substitution, so don't be surprised if they put more scrutinies on your case, read, REFs.
If your case is legit and your sponsoring company sound, even for LC substitution, you don't have anything to worry about. Just be patient.