My cat wants breakfast at 4am. I have been getting up to feed her then going back to bed. If I don't she keeps us all awake making as much noise as she can. I have ordered one of those automatic feeders and will set it to open at 4am. Hopefully that will resolve the problem.
I had been woken a few times at 1am or 2am. She has stopped doing that since I feed her more throughout the day with a small meal before she goes to bed. She is going to her bed quite early in the evening. I probably need to keep her awake longer.
Ah - he's doing the on demand as an attention-getter then - don't give in to that.
I'd actually start a routine for him. (They like routine even though the first few days may be .....uncomfortable.)
Decide what he's to have in terms of his quantity and how often it's practical to give it to him. Many cats like to be fed just a couple of times a day but some cats like smaller but more often. (My own Seniorboy is pretty old and an indoor cat so he has four and a half wet-food feeding times a day which I can manage because I work from home.)
How old is he? If he's very young, he might prefer to have small but often at the moment and change later on: it's not always easy for a little stomach to keep going for all of the evening and night-time also.