The earliest you can apply for OPT is 90 days before you get your degree, but no later than 60 days after you get your degree. Your OPT Employment Authorization Document (work permit) will be valid for one year. Because computer science is in the STEM field, you will be eligible to get a two-year extension of OPT, STEM OPT. The earliest you can apply for STEM OPT is 90 days before your OPT employment authorization is set to expire. I recommend you submit their application as early as possible. For STEM OPT, your employer will need to be registered in E-Verify - both you and your employer will need to complete a training plan for the new work permit to be applied. Take a look at this Ask Sophie column for more details.