Originally Posted by LchChester

For ex-HKG, standby starts at something like 6 or 7am that day for all flights within that operation day (i.e. including the "next day 1 or 2 am flight)

My experience:

On a CX J ticket with rebooking charge,
MNL - get on a 2 hours earlier flight free of charge
BKK - get on a 24 hours earlier flight (i.e. I booked the same flight the next day) free of charge

On an AVOIS redeemed ticket
NRT - being charged USD50 for getting on the flight, originally booked around 1 months later as return date was not confirmed when making the booking