The Brazilian boss has put his players through three days of drills and physical work in the early stages of their nearly three-week training camp in southern Germany.
"We cannot tell you (about any improvements). It is only after games that we can see progress. It's a process. And we will know more after one, two or three games," Parreira said at the team's hotel in Herzogenaurach.
South Africa hope to play three friendly matches during their stay in Germany, the biggest being a match against China on 28 April.
Parreira said he and the South African teams bosses have worked hard in lining up more friendly matches, but to little avail.
"We need these friendly games. Of course if we could play Brazil, Germany or England it would be better. And it would be better to get a match against a Bundesliga team. But I have tried since December. Nobody is willing to play one game at this time," he said.
The coach reiterated that his emphasis during this training camp will be to bring his side into top physical shape.
"We should be physically very keen and at the highest level. We need to be a fighting team. And we have to emphasize our strengths. We are good when we put the ball on the ground. We can't think about contact, we have to stress ball movement and tactics," said Parreira.
The former FIFA World Cup winner believes about 14 or 15 players of the 25-man squad in Herzogenaurach will make the team for the 2010 FIFA World Cup.
And he hopes to use the current camp to build upon the month-long session in Brazil to form a foundation for the team. And then after the European leagues are completed, his European-based players can come in and fit into the side.
"In Brazil and here we are defining the shape. And the players from overseas will fit into the shape," said the coach.
"We want to get the foundation set and then have the others come in and fit into the shape. If the foundation is solid, we are not worried," he said.
A problem Parreira does see is that many of the foreign-based players are not earning a lot of playing time. And that may pose a challenge come mid-May when they join the other players who have worked in camp since early March.
"It is not ideal. Those coming later will maybe play three games. The others had nine games in Brazil and three here plus the remaining three. And the overseas guys will only play at most three games. So having a player not playing for six months is a headache," he said.