Normaly Nightjet trains are not on time, due to works on tracks in the night they often get other routes every night. Wich one are you taking? And what day.
From Basel you can travel to Zurich (on the same Nightjet). From Zurich there are almost every 2 hours Eurocity trains to Milan (11€(2nd class) reservation needed for the italian part). Or you use one of the Intercity trains to Lugano or Chiasso and change there for the local express trains to Milan (you need the same time + you do not need a reservation)
Learn to be a little more clever: divide in planner up in segmets to see many more trips. And always best (why even ask?) the local planner-in this case sbb.ch-there are hourly connections direct from Basel to Bellinzona-Lugano-Chiasso-where ony can also board that EC-or in CH. the local free IT regionale.