Get all docs ready for your I-140 and I-485. I-693 can be got within 2-3 days (do TB test and asking X-ray directly in the same time you're from China). You do need LC paper signed by you and your employer for I-140 filing, wait till 9/27 and Fedex both I-140 and I-485 out using latest Fedex pickup on that day -- at least get a copy of your PERM approval notice like email or screen shot, and list certified LC paper in your cover letter to see if USCIS will let you pass.