I`ve finished a master degree here in Germany. I concluded my degree on october/20 but because the corona situation I received a certificate just on the the middle of January. Then, the company I wrote my master thesis offered me a job which I've already started on 01.03.2021.
I know I need to change my visa, but for the work permit visa I need my contract, a stellenbeschreibung and my certificate from the university (as informed by auslanderbehorde). I received the contract documents 2 days before start to work. Moreover, the structure of my salary (Tarifwerk) was not described and I needed it to proof I have the minimum as required for the bluecard . I've explained the company and they will provide that for me.
The main question is that I've already started to work with a student visa and I am planning to apply for a work permit as soon as I receive the document from the company. Is it legal to start working a fulltime job without a work visa, just with a student visa ? Which consequences could I face?