There are some new players who are still injured so he hasn't done the first game yet. If it's not fault he is Christopher Nkunku's, he injured his knee and had to have surgery. But it seems Christopher Nkunku will be ready for the International break match. If he does come back then it could be Pochettino's option in attack. Even if you look at Chelsea, they still need a lot of quality players according to Pochettino's character. They can still take advantage of the transfer break this season.
I have expected pochettino will be putting him in the main squad as soon as possible after doctor will be confirming if he can play against its opponent.
Many people are waiting for his debut caused by he has been showing impressive performance during the pre season.
Christopher Nkunku's individual qualities are indeed quite impressive and we could see him last season when he was still in the RB Leipzig uniform and so it is possible that he could help improve Chelsea's performance, but not now, he has just recovered from injury and needs to adapt and improve his performance.