I've downloaded the Mouseperks+ app on my Android phone, it opens Mouseperks website. I can open and choose parks, resort, DS, etc. Then I can see if a discount is offered for AP, TiW, Disney Visa, and DVC. It can also be used for shopping discount info.
As a rule, every time I pay, I ask "do you have AP, TiW, or Visa discounts?" It saves me a lot of heartache just to take a moment to ask while paying. But, I know that you are planning ahead, where I mostly am going there and if there's a discount, fine.
Just remember, TiW does automatically add a tip. I sometimes forget and add it again. Which wouldn't be all bad except historically it happens when the service is the worst and they should get no tip at all.