The United States has strict rules for international students who want to work during their studies. International students enrolled full time and in valid F-1 status can generally work on-campus for up to 20 hours per week during when classes are in session, and up to 40 hours per week when classes are not.
The OPT in USA allows students to stay back in the USA after completing their studies. For this, you need to get authorization from the USCIS and also from the international student office of the school. Under this program, the student is allowed to work for 12 months once she completes her course in the USA.
Submit your application for OPT in USA nine months after you have started your study in USA. However, students need to receive the Employment Authorization Document or EAD from the USCIS to begin working under OPT in USA.
According to USCIS, an application for permanent residence (Form I-485) will take anywhere from 6 months to 33 months to process.