The West Yorkshire outfit will take on Ipswich away from home at Portman Road in the Championship on Saturday afternoon.
Many Leeds fans will have expected De Bock to feature in the match, given that the 25-year-old left-back recently joined the Whites from Belgian club Club Brugge.
The former Belgium Under-21 international defender has arrived at Elland Road with a strong reputation and is expected to be a huge success.
However, Leeds fans will have to wait to see him turn out for the first team.
Christiansen told Leeds Live about De Bock: “He signed, he went back (to Belgium), but in a few days he will be back again with the team, ready to train and ready to join the group.
“It is an interesting player in the left full-back position we have been searching for, so I think he will be a good signing.
“For this game against Ipswich it will not be possible (for him to play). But for the next week there is good possibilities.”
Christiansen has also given an update on which other players are not available for the match against Ipswich.
“Pennington is sick, he has been sick a few days and it's not fit for this game,” Christiansen told Leeds Live. “Caleb is still out and will need some time.
“Ronny is doing quite well, next week we expect him to be with the team. Stuart Dallas is in the in squad and we will see if he has the possibility to start in the eleven.”
Ipswich are a hard team to play against away from home, and Leeds are going to find it hard to win at Portman Road.
However, if the Whites score the opening goal, then they should be able to at least pick up a point.
Meanwhile, Leeds legend Eddie Gray has given his take on the signing of De Bock, and told LUTV: “I just hope he is as good as some of the Belgian players who are playing in the Premier League.
"That would be a big bonus because there are a lot of smashing Belgian players playing there now.
"He comes with a fair reputation. He has played at a high level there. He has won trophies, so he knows what’s it's all about.”