I can't post links, but this might (not) help:
Pursuant to the German Residence Act (Section 39), consent for the issuing of a residence title
for employment may strictly only be granted if:
- the foreigner's employment would not result in any negative effects on the labour market;
- no German workers, nationals of EU/EEA countries or Switzerland, or foreigners considered as legally equivalent to German workers with regard to taking up employment are available for the employment (priority check),
- the foreigners are not employed with worse working conditions than comparable German workers.
The local Employment Agency carries out the priority check. It checks whether preferential applicants are available on the regional and wider (EU/EEA) labour market and that the conditions of employment offered to the foreign workers are not worse than those of comparable employees. To this end, a detailed job advertisement must be submitted to the Employment Agency in good time, in particular providing information on the intended conditions of employment.
The question as to whether a vacant position can be filled with a foreign worker should usually be clarified within two weeks. This time frame assumes that the employer has already supplied all necessary information.