Journey Date is SCH Departure from Boarding Station, irrespective of its Departure time from starting station!!!
If its for tatkal, then u can try it from Pune too, with 21 apr date, as its sch DEP time is close to mid-night.
To be safe, u can book from Lonavala & get the boarding changed to pune from PRS Counter, anytime b4 24 hrs of scheduled dep from Lonavala!!!!