Milik already on the pitch.

Arkadiusz Milik

Arkadiusz Milik on the pitch on 22 January against Milan.

Possible guess, according to the today’s edition of Corriere dello Sport. The important sports newspaper writes about the positive feelings which you sense. The knee is responding well for the everyone’s surprise. Therefore, it would not be excluded the Milik‘s return after just 100 days.
In the first, Arek has surprised the Napoli medical staff. Next week there will be another visit to Villa Stuart by Professor Mariani. Arek could return to train in the group just after Christmas, around January 15 next year.

Then in the pitch on January 22 against Milan.