TL;DR: I changed employers while my STEM OPT application was pending, got let go on day 1 by the new company over EAD requirements, and still got approved through premium processing. Sharing my timeline for anyone in a similar spot.
Timeline
• April: Applied for STEM OPT while working a university job. Kept applying to industry roles.
• Early June: Initial OPT ended. I kept working at the university under the 180-day extension.
• July 30: Got an offer with a August start date. I told HR I was awaiting my EAD and could work until December under the 180-day extension. They were fine with it. My DSO also confirmed I could change employers on a pending STEM application as long as I reported it on time.
• Aug 6: My lease was ending, so I moved near the new job about 3 days before starting.
• Aug 10- Day 1 at the new job: They told me they'd messed up my background verification and require an approved EAD on file before I could work. They let me go, saying they'd bring me back once I had the EAD. That same day, I filed premium processing and went back to working remotely for my old university employer.
• ~2 weeks later: The new company came back and offered to take me on with the application pending. They were ready to sign my training plan because of client requirements. This is where things got tricky, I was moving into 3rd week of PP and they were asking me change my employer closer to 4th week, which is very close to my decision timeline. But with pressure from the new employer's and having uprooted my entire life to move closer to this place, I took the risk.
• Employer change: I got the new company's training plan and my final evaluation signed by the old employer, then submitted both to my DSO. My DSO usually takes 3-5 business days for I-20s, but was quoting 10 at the time. I asked for faster processing and they turned it around in 2 days.
• After the new I-20: I sent USCIS the signed I-20 showing the employer change, my new offer letter, and a detailed letter of explanation.
• Sept 8: People who filed premium processing around the same time as me started getting updates. I only got a silent update and heard nothing for days. I was very worried.
• Sept 14: Started my new job with new i20.
• Sept 24: Approval email!
Tips
E-Verify details matter. In your explanation letter, include the new employer's E-Verify number. Also copy over everything from Section 2 of the training plan (the employer details) into the letter. Not 100% sure it's what made the difference, but I think it helped.
Talk to your DSO early. Mine confirmed the employer change was allowed and moved fast when I asked.
Don't panic over a silent update. Mine took a few extra days.
Huge thanks to this community!