General coaches are a hell. Gets fill up to the brim (but still lesser crowd than Indrayani exp) from Pune itself. Worst even on Weekends or Festive time.
So if you wish to travel between Pune-Mumbai/Dadar , then book a 2S seat. The tickets are generally available even at morning on the journey date. But do book in advance if its weekend or Festive time like Shiv jayanti or Ganpati.
CC are generally available all the time and its CC has good cancellation rate.
PS:...
more... If you have to go from Pune-Mumbai CST/Dadar , then don't opt afternoon Deccan. Instead Take this train as Deccan take hell 1hr excess to cover Pune-dadar stretch and gets heavily crowded in reserved coaches also.