The EB3 is backed up for years for every country. No, you cannot work while "waiting for Labor certificate."

Ok,
So what kind of visa do you suggest me to get in order to obtain the permanent residence? My employee is thinking about an H2B, could it be working?

Thanks for your help!

H2B is all used up for the current fiscal year. The H2B is a temporary visa and cannot be converted to a permanent one like the H1B.

Thanks Ronnie!
So I think we will have to find an other way...My boss also proposed me to go there (California) first with a Q1, then he would like to get me an L1 to transfer me from Mexico (I am supposed to go there from California, always with the Q1) to the US and finally appling for the Green Card.
He basically is looking for people who can stay and working in the States for a long time, without going back and forth to their originally home countries becuase of temporary visas...
Is that possible in your opinion switch from an L1 to the permanent residence?
Thank you so much!

A Q-1 cannot be coming for the purpose of immigrating to the U.S.

An L-1 is an intracompany transferee. You must have worked for the foreign subsidiary, branch, affiliate for at least 1 continuous year within the past 3 years, and otherwise qualify either as an employee with specialized knowledge of the company or as an executive/manager of the company.

You (or your prospective employer) need to contact an immigration attorney and see what options, if any, are available to you.