Yes, the strict solar schedule is beginning to 'take' - and it only took 25 years of my repeating it
The funny thing is that canary keepers knew all along that birds need to follow a solar schedule (canaries have been kept and bred by humans since the 1400's) but it took many years for parrot keepers to 'catch up' to their knowledge. But I think it was not only the fact that parrot breeders did not care about it as it was convenient to them that the birds were hormonal all the time but also that people thought that ALL parrots were tropical and they figured that if they lived with 12 hours of day and 12 hours of night in the wild, it was OK to do it in captivity. Of course, this did not work because, in reality, there is a 20 minute difference between the seasons in the Equator (and we now know, from studies, that birds register that 20 minute difference) but also that, in the wild, there are two more triggers, food availability and weather, which disappear in captivity.
Now, make sure that the bird is exposed to dawn and dusk for 2 whole hours without any artificial light because it is the different light that happens at twilight that turns on or off their internal clock.
The weight is good BUT weight is not everything because an out of shape bird can have perfect weight, too (fat weighing less than muscle).
PLEASE PLEASE PLEASE do NOT attempt to potty train your bird. In all honesty, if anybody cannot live with a little bird poop, that person should not have a bird! Birds metabolisms are too fast for potty training (they literally poop every few minutes) and they excrete everything together (urine and feces) so, when they 'hold it', the lower part of their intestine becomes compromised and there are birds that have ended up with cloacal prolapse from it. We have a member who ended up paying thousands of dollars in surgery to correct the prolapse in a cockatoo she had rescued. Birds poop is a clean poop as long as you do not feed animal protein -which you should NOT because, contrary to popular belief, they are not omnivores but herbivores and did not evolve to eat any animal protein. No animal protein means no E.coli bacteria so no human is going to get sick from it. And it washes very easily. I have a number of birds out flying every day for hours and hours and, yes, they do poop everywhere but all I need to do is scrape the dry one and then wipe or just wipe the ones that are still wet once they go back into their cages. I have a system. I sweep the floors while scraping the dry poop off the floor with a little plastic spatula (like the kind you get at Home Depot to spread compound on little holes), I spray the poop spots with warm water that has a squirt of dish detergent and a drop of Clorox (this is the same mixture I use to spray the 'dirty' spots in their cages) and I then mop with a damp cloth that has a squirt of either lemon or lavender oil. Easy peasy lemon squeezy, clean floors and nice smell!
Yes, a bird will tolerate a 2 hour drive but look for vets that treat exotics without being certified - you might find one that is near to you.
Oatis is a wonderful name BUT if you know the name he had before, I suggest you use it because birds understand the concept and use proper names of their own (there is a study that shows that parents name their babies in the nest and that the babies continue using the names all their lives). Now, there are birds that never actually learned that the name given to them by their previous owners was, indeed, their name (I have a few of those) so listen to the sound he makes when he wants attention because that IS his name. Keku Quaker was called Gryphon in her previous home but she never recognized this name as her own so I listened to the sounds she made and realized that her real name was something that sounded like Ke Kuh - and that became her name! Same thing with Cheeks Caique. His name is actually Beshe or Beshe Beh but, when I call Javi (which was his previous owner's name and which, to him, means 'human') he answers me and comes to me (because birds will 'announce' themselves by vocalizing their name first when approaching others so, when I call Javi, he thinks I am saying my name and that I want him to pay attention to me). And Condorito Caique whose real name is Epuish, according to him... or Linus Too who thinks his name is Hello and people are Hi, Linus
People tend to think that parrots are like dogs and that you can change their names without a problem (something I also would not do to a rehomed dog, mind you) but it's not so.
So, if I were you, I would call his 'old' name and see how he reacts to it and, if he doesn't, listen to the sound he always makes when he wants your attention because that will be his name.