Before you apply the sealant, you want to wipe the paint down with either IPA (Isopropyl Alcohol) diluted with distilled water 10-15%, or Carpro Eraser.
What this will do is remove any residue left from your clay lube, oils, or soap residue on the surface, giving your sealant the best possible surface to bond to.
This step is critical to get maximum longevity out of your sealant.
Think of sticking 2 pieces of tape to something. One area is completely clean and free of any residue. The other is clean, but has some residue on it. Which piece will bond better? Same concept when applying protection.
Prepping it properly before applying you should get at least 4 months out of it on a garage queen.
You'll know when it's gone because the surface will no longer bead or sheet water.
Since your car is a garage queen, I'd highly recommend Ultima Waterless Wash Plush concentrate and a good California duster for cleaning the dust off, which with a garage queen, this is mostly what you'll get on the car.
Many people say the CD is a bad product, that it will scratch paint. It will if used improperly. Here's how to use it right.