Thanks everyone. I'm not a good reader, so I entered at gate 5/6 as recommended and then went to the regular Jet Airways check in lines in front of me and then asked the line staff where business class check in was and they directed me to the dedicated first/business check in area off to the right.

Check in, security and immigration took about 5 minutes, so in my limited experience there is absolutely no reason to arrive at the airport 2-3 hours early if you're flying in business/first class.

Having upgraded online, I did feel like a "second class" Premiere class passenger. When I checked in at the business class area, the agent asked if I had used miles for the ticket. I wasn't allowed access to the GVK lounge, because if you upgrade online you don't get that.

I was in seat 2F and when the flight attendant took everyone's dining orders she asked the guy in 2D and then skipped over me and took my order I think 11th of the 12 business class passengers.

They did not pass out Bangkok fast track immigration passes (or even landing cards) to anyone and Bangkok immigration staff won't let you use the premium lanes with just a business class boarding pass, you need the fast track pass. The line at Bangkok immigration area 3 looked to be about 45 minutes long so I walked 50-100 meters over to immigration 1 and the lines there were much shorter.