This really depends on the time of day. There are some times when they're more interested in vocalizing, preening, flying or playing. Mine don't eat at consistent intervals.
This.
The closest I have to bird "meal times" is with my Quaker, Gus. He's a bit of a velcro bird, and when I'm around, he sometimes forgets to eat, and then gets all grumpy because he's hungry. When I can tell he needs to eat, I'll shut him in his cage for a few minutes, at which point, he'll be like "oh yeah! I have food!" and stuff his face.
Even that, though, doesn't give me a good idea of "standard" food intervals, because he doesn't eat the same amount at every meal. He also dunks his pellets in his water bowl and there's a lot of waste, so it's really hard to tell how much ends up in his belly vs. drifting in the water bowl or turned into dust and crumbled on the floor of the cage.
I don't watch the clock or his food intake - I watch his poop. When I notice his poop getting small, I know he's overdue for a snack.
If you're concerned about your bird being overweight, the best solution is to make him work for his food. This can be as simple as putting food at one end of the room and water at the other so they have to fly between the two. Of course, foraging toys are the gold standard for using food to encourage physical and mental exercise.
