My hubby, with dementia, gets up at 3 am and dresses to go out. He fusses at me from then on to hurry up and get dressed and get ready to leave. This is no matter when his doctor or other appt is scheduled. We often leave home by 4 am and spend the day waiting in the doctor's parking lot for a 3:30 pm appt. If I "spring" the appt on him when it's time to get ready to leave he refuses to go because I didn't tell him about it the day before! I've tried showing him on the clock, setting an alarm for time to get ready, x number of hours before time to leave ---- everything I can think of. He is just like his mother in this --I also took care of her in her later years.
One suggestion... don't tell him about the appt...get him up and ready, tell him ya'll are going for an early breakfast.... then take him to the Dr.... you can even get breakfast if you want..... the hardest thing for us to do is not jump to every demand or delusion they have..... I hope others share their thoughts on this.... we can never have to many choices to fall back on.... hugs to you...