I believe Changi Terminal 2, Transfer E desk, does not open until 8am. So you may not be able to get return boarding pass as soon as you arrive. But plenty to do and places to relax in the 60 minutes or so during your wait.
What did your RT price out at end? Did you use miles + cash for upgrade on return segment?
Safe travels
GDL - Thanks! $515 roundtrip then $450 + 30k miles for the return upgrade. It cleared immediately. R=1 still on this flight (April 30) - R=5 when I booked it.. When I booked it the other day, I noticed Singapore, Shanghai and Tokyo all had R space available