He admits it would probably have come a lot sooner had United enjoyed a smoother start to the season.
"I would have played him three or four weeks earlier, but I didn't feel at the time the circumstances were right to put him in the team," said Moyes.
"But I think part of this job is to introduce young players. When you're in the dressing-room area, you see Sir Matt Busby's comments on the wall: 'If they're good enough they're old enough'.
"It has been the philosophy of this club.
"The last manager put young players in when he had them, and if I've got more young ones I want to play then I will try to bring them on because I think it's what they do well here.
"It's important to remember he's still only 18. Some players will play for clubs when they are 18, but I think to play for Manchester United at that age is a big thing.
"Time will tell what his best position will be. He could arguably be a centre forward, he's that good with his back to goal. He's also very good coming off the left and off the right, maybe in the No 10 role when he grows with experience.
"He's got no real ego to him. He's a really humble boy and he's been really well looked after by his dad and his family. That's kept him the right way. I think he can handle anything that comes his way.
"I've had words with him since Sunderland and spoken to him about what he has to do. With young boys there are going to be dips at times and there will be games when you see it. We will try to make sure we look for that."
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