For what its worth I will clip the wings of any bird that I intend on taming, (unless its a baby). I find it keeps them out of danger until they are use to you and your house. Both of our Budgies were clipped and within a few months they could fly perfectly. Jazz our Cockatiel has also been clipped and he can still fly (Strong Wing Muscles) but has trouble gaining height. He does fly from one end of the house to the other.
The first Budgie we got, the breeder clipped only one wing. They are supposed to go off balance and this discourages flying. What I found was the bird couldn't land properly and it would still try to fly, so we clipped both wings so it could land safely. I don't like the idea of clipping one wing.
If a bird is already tame and relatively relaxed around you I wouldn't clip its wings.
My Conures are well over a year old and never been handled at all. There is no way I would try to train them without having their wings clipped (for their safety). Mind you they can both fly but they have to work hard at it, so the age of the bird is another thing that needs to be factored.
I would read up on the subject and get as much information as you can. I know when I purchased my breeding pair of adult conures the breeder thought I was nuts thinking I could tame them. This is from a guy who has been breeding parrots for over 50 years. One is already tame. So understand an expert is only an expert based on their limited life experiences. Good luck with it
Well that's my 2 cents worth

PS: I would leave the first to primary feathers because the look better with the wings folded and they seem to be able to balance and manage landings much better.
Cheers
Paul