Dropped bags at SIN well before 16:00 for BA12
Early bag drop info screen at SIN
Also a screen (next to the one pictured above) advised F, J and OWE could check in at a dedicated VIP area. We did walk along to this room afterwards and sure enough we could have checked in here. We still managed to walk through the area directly to the passport scanners avoiding any lines.
So - if you want to check in for your BA flight v early, head past check in area 4, through to a darkened VIP room with desks and a backdoor through to passport control.