How is the immigration procedure at Guarulhos airport?

I am Brazilian and my fiancee is Canadian and we are going to Brazil to spend 1 month.

I am concerned about the immigration at the airport; I don't want us to get lost from each other during this procedure, since we have to catch another flight just 1:30 hours after our arrival and it will be a big rush. So far I know we don't present ourselves to the officers in the same place; but can we get together easily after we go through them? Is there a "meeting spot" or any other reference spot?

Yes you will go through the immigration separately. One line is for Brazilian citizens and another one for Foreigners. You can, perhaps, ask an officer if you can stay at the same line with your fiancee and wait together but I am not sure.
Otherwise if you are afraid of missing your next flight, that's what I would do:
you will go trough the immigration really fast because you are brazilian. Your fiance will wait in line for the procedure which can take a while depending on the length of the line. They are doing fingerprints now so it can take much longer. Meanwile, go get your suitcase (if you are getting in Guarulhos) . Tell your fiance to wait right where she pass the immigration, not to leave and wonder around the airport.

good luck.

It will be no problem for you. You will pass immigration separately because you are a citizen, but from there you proceed to the baggage claim area. You can pre-arrange to meet at your luggage carousel, the restroom, currency exchange. Don't worry!

I'm South African, and passed there twice with my (also South African) wife. Easy peasy. Yes I know you will stand in seperate queues..read on:

Where to meet? No problem at all. You can just meet at the baggage reclaim for the flight you will have disembarked from (even if you don't have baggage to reclaim, it's an easy reference point to meet).