United meet City at Wembley at the Community Shield with Zirkzee potentially making his competitive debut.
Ten Hag said, "Yeah, we had actually only just one or two team training (sessions), where everyone was there. So yeah, it was a very short period. Last week for four days he did an individual (programme) then he did for three days, group sessions and now we are 100 per cent with our team. So it's a very short period to assess this.
"I think it's (the same) for every player who is coming into a new league, into a new club and it takes time. I think also for every player to go into the Premier League, we all know the intensity is higher in comparison with the leagues where they are coming from, but he is already experienced. He was a player in Germany, he was a player in Belgium, he was a player in Italy. He has already collected a lot of good experience and that will help him.
"But still he has to make a step and we have to help him and then you see it's not like, say early days, that you have a proper pre-season with the team and it's not you went to the Euros so you had to train on his own individual (plan) here. He and we need time to fit him in and that will take some weeks."