Two hours should be sufficient time. Over the past few months my flights from the USA would land at GRU at 7am. Around that time LH, JJ, BA and AF flights land, so immigration can involve a bit of a wait. The longest I have waited has been one hour. I would then connect to a 9:15am RG flight to CNF. So, as soon as I got my suitcase from the baggage claim (in Terminal 1), I would walk (and sometimes very fast) over to Terminal 2 to check in with RG. There is a JJ & RG transit counter as soon as you exit immigration in Terminal 1, but that line is always long. For me, it's better to head over to RG at Terminal 2. Walking time between T1 and T2 is about five minutes.