Nicolelis said he and a team of some 40 people have barely left the lab since March, when they arrived in Sao Paulo, Brazil's largest city and economic hub, to finalize preparations.
But it's been rewarding, too, he said, recalling the moment on April 24 when a paralyzed user first took steps in the exoskeleton.
They named the device the BRA-Santos Dumont, a combination of the three-letter sporting code for Brazil and Alberto Santos-Dumont, a Brazilian aviator, inventor and bon vivant who once demonstrated controllable flight was possible by flying his dirigible around the Eiffel Tower.
Some scientists have criticized Nicolelis for ditching academic publications in favor of mass media -- he posts research updates on Facebook -- and the anonymity of the lab for the lights of the World Cup stage.
Critics have also questioned the practicality of his research and accused him of hogging an unfair share of the Brazilian government's research budget. Nicolelis rejects that criticism.
"The funding is the same with or without the World Cup. We've received $14 million from the Brazilian government over the last two years. That's approximately four or five times less than what the United States government invests in a mechanical arm," he said.
"I don't see anything wrong with demonstrating a technology for the whole world that has a humanitarian objective and was paid for by civil society," he added.
More than 65,000 people will be in Sao Paulo's Corinthians Arena to watch the BRA-Santos Dumont's first steps in public before Brazil play Croatia in the opening match. Around a billion are expected to watch on TV.