Van Persie reflects with fondness on his time with Arsenal, where he scored 132 goals in 277 appearances, but accepts that the moment was right to move on to United and challenge for trophies.
He said: "It was just time, I think Sir Alex said it last week, he said literally that 'Robin is here at the right time, the right moment and the right club.' I do feel that.
"I do feel that this is exactly the right timing of being here. I don't think it was better to come here earlier. I think everything went this way for a reason.
"For example, when I extended my deal a couple of years ago with Arsenal I did feel that was the right move, to stay and to play because I wasn't finished there.
"Now, since last summer, I had a great feeling to go for a big challenge, and this was the biggest challenge for me so far."