The Dutchman would not commit to talking about how many players may come in or leave.
However, he did suggest that as he continued to assess his squad, more deals may happen later in the window.
He told reporters: “I think I said before that the first aim is to work with these players. Of course it's a disadvantage that many of them are not here yet, I mean the players that are already under contract.
“The positive about that is that it's an important lifeline of the club that youngsters come into the team as well, so it's an ideal way of seeing them in these weeks, where they get a lot of playing time as well.
“The standards are really high when it comes to bringing in new players because we have such a good team and such a good squad.
“Of course Richard (Hughes) and me and other people as well are trying to improve the squad where possible, but that's not that easy because we have so many good players.”
Asked why the club have not yet signed a player, he added; “The first one is one of the reasons, me wanting to assess the squad, which is difficult because most of them are still not here.
“And the second one also has to do with the difficulty (that) if you inherited a team that is really good then it's not so easy to find players that are of the same standards or even higher, especially because those ones need to be available as well.
“But like I said, Richard more than me is really working hard on that as well and he keeps me updated every time. If there is any news on that, we will come to you. But like I said, we already have a very good team I'm already really happy with.
“But it would be a surprise for all of us I think if we don't bring any player in, so that will probably happen in the end. But for now, we are just waiting for the players to come back and waiting for the right ones to sign.”