Welcome and be welcomed. Congrats in your lovebird! THere are 2 causes for this type baldness. One is medical, which is rare, and the other is called plucking. Plucking means the bird is doing this himself. There are many reasons they do this, some mental (yes mental!) and some from stress and others. So I would, if possible, take him to a Certified Avian Vet (no dog & cat vet!), but I see in your area that might not be possible. That would rule out a medical cause. The other cause, self plucking, is really , really hard to prevent. Let him settle down in his new home for a few weeks. Try to observe him actually plucking, note when he does it. After he has settled in, and you are a good long way to establishing a strong bond with him, tr and provide him with toys that will allow him to possibly take out his urge to pull feathers out on the toy, rather then himself. Another way is to get a small flexible collar for him (much like a dog shield type collar) which would prevent him from being able to reach his feathers. Using one has its own downsides (he will not be able to preen his feathers at all, so he will need help keeping clean) and getting to food bowls may be a bit challenging. Getting him used to a collar has its own stresses.
But take heart! Many parrots that are pluckers live long, and happy lives, with owners who love them! PLease search the board here, using the search function, to get more info on plucking and its causes and ways to deal with it.