I wish I could give you some good advice, but I can't. I have a bulldog that at 4:30 am on the dot also will choose to do her business. Could she just wait 30 more minutes until we get up...no, she has to go then.
We tried changing her dinner to later and it still does not work. The babies on the other hand, can hold it all night from 10-5 when I get them up.