The former Netherlands coach stated when he was arrived at Old Trafford that it would take him three months to make an impact at the Premier League club.
Van Gaal has been faced with a major rebuilding job and the 63-year-old admits it was unrealistic to expect he could transform the club in such a short space of time.
"I have said it was very stupid to say three months because then you [media] are only talking about three months." he said.
"It is always the performance that counts, but the performance always goes up and down. Then we rise. When that date is, or what that match is, depends."
United have brought in the likes of Angel Di Maria and Radamel Falcao in attempt to turn around their fortunes after a disappointing 2013-14 campaign, but Van Gaal knows they are far from being the finished article.
He said: "You have your hopes but I do think there are stronger teams in the world now.
"We have to make a team and that's why I have a period of three years. I hope we can fulfil the dream we have. Chelsea has already a lot of time.
"When you have three months with 10 players injured you cannot have a big progression. You are always playing with a different team.
"I don't think that 11 points out of seven games is better than I expected. I think it is good enough to be in fourth place and nothing more."
United face West Brom at The Hawthorns in the Premier League on Monday.
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