That being said, I will share with you the steps that I used to potty train my Jenday Conure, Mischief.
I started him when he was young and it was a fairly easy process. I can not really tell you how long it would take with an older bird, but I do know that with any age bird, it requires a lot of patience, praise and rewards.As babies, you can figure that they are going to potty on the average of every 20 minutes (give or take). They will also normally potty when you first take them out of the cage. So, be prepared for this. Have your paper or whatever you are going to use handy for the bird to poop on. We use a
wicker basket with a handle, then I attached a ladder going up to the handle. About every 20 minutes we would set him on the basket. Decide ahead of time on the key words that you want to use when you are telling him/her to potty. With Mischief we say, "Be a good boy." Then when he uses the potty we praise him and give him a treat. Eventually, we were able to phase out a treat everytime, but you always praise them when they follow the rules or do what you want. (Just like children.) Now, he just climbs the ladder and goes to potty on his own without being told to.
But, like I said, you have to remember to be patient. All birds are not going to learn at the same pace. It will take some longer than it does others. The basics of this can be used to teach your bird other things as well. For instance, pick out your key words that you want to use to indicate to your bird to do a trick, then stick with it. When the bird gets the idea and starts doing it, always praise it, then give it a treat that it likes. Be sure to pick out treats that are healthy though, we don't want to get fat unhealthy birds in the process.