"proper" method of bullnose around tub/shower surround?

I am putting some 4.25" ceramic tile above the tub/shower surround in my kids' bathroom. I was wondering what the standard or proper way to align the bullnose in respects to everything else. The bullnose I have is 6" tall, not 4.25"

Does the bullnose start with a full piece at the ceiling and then the bottom piece get cut to fit? Or the other way round?

Also, I saw 4.25" square tile with a bullnose edge at the store, too. I wouldn't use that square bullnose above the shower surround and then the longer 6" on the side of the surround?

Or, am I off in using the 6" bullnose on the side in the first place. Is this not usually done?

Here's a picture:

 

You don't want to mix two different size bullnose tile there, 6" is fine. The top is the most visible so starting with a full bn tile at the top is a good idea unless it leaves a small piece at the bottom. Do the layout the way it pleases you the most.