1-gallon batch hopping advice needed

I'm planning on doing some experimental 1-gallon batches with DME to learn more about different varieties of hops - sort of like SMASH, but using DME instead of grains. I want something quick & easy to make & repeat, and it's too much work with all-grain for such a small quantity.

I'm using Briess Sparkling Amber DME to give me an OG of 1.053 to give me something like an American Amber. Going to use Nottingham for the yeast. I want to maximize hop aroma & flavor so I was thinking off something like:

0.5 oz centennial @ 10 min ~25 IBU
0.5 oz centennial @ 5 min ~15 IBU
x oz centennial dry hop 5 days

The goal here is to repeat this using a different hop variety each time to get to know my hop aroma & flavors better. What I don't have a handle on is the dry hop quantities.

I currently have Cascade, Centennial and the DME on hand, so I'm locked in for the first two batches for now.

I'm looking for some feedback on hopping schedule and any other ideas I might want to consider.

Thanks!