Van Gaal insisted that he would give the team's young players a chance at his first press conference, and Blackett has since completed all three of United's Premier League fixtures so far this campaign.
"I've played in some good teams and it has been a good learning curve," Blackett, 20, told The Sun on Sunday.
"I sort of expected it after the way I played in pre-season. I know I did well and the team got some good results.
"The new manager always said he would be interested in young players and I knew that I was in with a chance."
United face Queens Park Rangers in Premier League action next Sunday.