Visa Change/Job Question

Hi,
I'm not sure if this is the right page to post so please delete if not relevant.

I recently receive a job offer that requires me to change from instructor to another one. The company that offer be the job told me they can wait for me to submit my resignation letter when the visa change has been approved. I'm just wondering when the visa change gets approved from instructor to something , doesn't that mean I cannot go to work for my current job (holding my instructor visa) the day it gets approved?

by Due-Sky-4288