EB2 to EB3 - Green card application?

[GCdreamer0612]

I have approved 1-140 EB2 category - India, Now I moved to a new job and restarting my GC process keeping the previous Priority date. Looking at the monthly visa bulletin, EB3 movement is more and is advancing faster than EB2 for India. Can I change my category to EB3 from Eb2 and  When? 
Currently the new employer is filing my labor. When do I specify the category. 
To be safe, I'm applying in EB2 for labor but can I change category to EB3 when applying for i 140? 

Your help and suggestions are appreciated! Thanks in advance. 

[xTDx]

You do not specify anything. Your employer and employers attorney will decide what category the new job falls in. Its not your skills that decide the category but the job responsibilities and its minimum requirements.  There is no category at labor stage. Best tip is to talk to your employer and their/your attorneys.