Hello, I came to USA 1 and a half years ago with a H1B visa for doing a clinical fellowship. Now I have matched for residency and have to start training on July 1 st. I have started application for a J1 visa (only visa issued by the university) and have 3 more months of H1B. I expect to receive form DS2019 in a month's time. Should i apply for a change of status (I-539) or should i go back to my home country to get visa stamping done. What is the current wait time for processing of I 539 and can i start training when the change of status petition is pending for approval?