Rio Carnival 2014 will start on February 28th of 2014.
There are grand rehearsals that take place on the samba run-way in the Sambodromo itself. It is almost like the Samba Parade without costumes and floats (they are replaced by busses) and with less participants. They start in December and there will be a few almost every weekend.
The last rehearsal in the Sambodromo takes place last Sunday
Sunday, February 23rd 21:00-23:00
Testing of lights and sound with the Samba School Villa Isabel, the 2013 Grand Champion
You can go and watch it. It's free. You can try most Grand Stand sectors although it will be very busy. It is a good opportunity to warm you up for the great party that will develop during the Samba Parade and see it all in preparation.
After the rehearsal, there will be a large free street party with very good live samba music and people dancing on the samba run-way. Some wear costumes and colorful dresses. It is an experience.
Outside the Sambodromo there is an eating area (Brazilian style - do not expect any sophistication) which includes small barbecue and drink stands. There is lots of booze and cheap food. The essence of Brazilian life.