It seems to be before 11pm server time. But it is still undefinite. I have seen changes up to 10.30 pm server time be taken into heaven palace. I have also seen that a change after 11.15 didn't make it to palace.
To be safe though and take in account that not everyone is online at every moment of the day a good point to do it is after events where many are present such as cerb, baal or gw.