You are in for quite a shock... Every flight from south america, from every airline arrives at this time.. It's the worst immigration in the US. JFK-GIG is my commute(still longing for the JFK-GIG non-stop aa used to have)..

Here's a few tips..

I always go JFK-MIA-GIG (Arrive much earlier in Rio) on the way down and GIG-GRU-JFK on the way back. The JFK immigration is painless. It really is the first plane in the morning at JFK. It's almost always early and you have to wait on the plane until 06:00 for immigration to open. I've gone from the plane to the street in less then 5 minutes. 15 with check bags.

When you do the JFK-GRU-GIG route, you have to get off the plane in GRU, but sometimes getting to the AC is a little tricky. When you get off the plane, you have to walk ALL THE WAY to the end of the terminal to get to the AC. SOMETIMES (I stress sometimes because it's about 50-50), halfway down the hallway, GRU security will open up a little both to scan your bags and let you back in the terminal. There's usually an AA person here directing everyone with connections to go through the security checkpoint. DON'T DO IT because you're not allowed out to get to the AC!! Just keep walking strait to the end, and go up the escalator to the AC. The club is empty at this hour. The only activity is connections to Rio and the day GRU-MIA flight.

As far as the upgrade goes, 25/26 upgrades in the last 18 months cleared at the gate. Make sure you get to the airport 3 hours before the flight to be first on the airport list if your upgrade doesn't clear in advance. For the return, the AC in GIG cannot process the upgrade if you're connecting in GRU. I've sat in coach many times for the 25 minute hop to GRU only to have my upgrade clear for the JFK leg. A 25 minute flight on a 777 is pretty neat though.

The delay is for transferring cargo and waiting for connections from Dallas. Very few people connect from Miami because there's already 2 non-stops to GIG.