The Saints sold a number of their key players over the summer, but currently sit second in the table after winning three of their opening five matches.
"It's a surprise to have got off to the best ever start in the league after going through so many changes in the summer," Schneiderlin told the Daily Mail. "The coaching staff changed, a lot of players left so of course it's great for us to be in such a good position after five games, but it's only five games of a long season and we need to keep going.
"We had a very good start last year as well but it was difficult after going through a hard time in December and after that it was difficult to get back up the league. We're going to try to be stronger in that period.
"The group is closer after the summer, a lot of people were saying that Southampton would struggle this season because we lost so many players."
Southampton are next in action when they visit Arsenal in the League Cup on Tuesday evening.