I see some light here. 1. You can change similar job only after 180 days of filing I-140. If I-140 is not approved by that date, you can use the AC-21 portability rule and can find employment similar job and keep the priority date. Although your employer may revoke I-140 after that date, you will be required to give evidence of being employed by another employer without jeopardizing your green card application process. 2. In your case, you filed I-140 and are laid off in January. Forget about it now. It's no use anyway. 3. Had you been on H1B, and laid off, you had problem due to layoff. But you are in CPT/OPT, therefore, you are back to your status and can find a new job before your CPT expires. 4. It's good that you didn't file the I-485 concurrently. Otherwise, you would be out-of-status on the day I-140 is denied (without an H1 backup). 5. My advice: Forget about this I-140. Find a new job, file for H1B before your CPT expires using premium processing. Then proceed to green card application as the second step. It is risky to file for COS (Change of Status) to LPR (Legal Permanent Resident) without having a dual intent status (such as H1B).