[My query is about PNR 6722019553 for train 22415 VSKP NDLS APEXP]
You will get your berth/coach details on your journey date. At the time of chart preparation, IRCTC will send SMS giving your journey details along with your seat and coach.
This generally happens when just before booking time seats are in waiting and at the time of booking it becomes available (When someone cancels their ticket at that time). So IRCTC does not issue ticket just at the time of booking and fits in at chart preparation time.
Since your ticket is confirmed, you will definitely get seats. Even if you don’t get SMS from IRCTC, you can just type in your PNR on any train related app and can check your seat details on your journey date.