Tentative travel dates

Here's the scoop. It's complicated, so I'll try to condense it. We have a consulate appointment on September 28 which means we'll leave on the 17th. These are tentative dates because if our amended I171H doesn't come in the mail between now and the 16th, we can't go and we'll have to reschedule for late October. All we can do is be ready and hope for a miracle that USCIS expedites our request. SOOOO STRESSFUL!