The best advice I can offer is make your check list, use some of the excellent advice offered by others above and firmly have in your mind that you are going to walk away without making a final decision. Just give yourself that 24 hour time period to make your decision unabated by having a certainly enchanting kitten in your lap or at your feet.
If you walk through the doors to meet a kitten thinking you'll make the decision when you've seen them, you are definitely toast and will be walking out the door with either a kitten or a signed contract. Savannah kittens have extraordinary powers at this young age and a definitive cuteness that hides their intent. They will eat your food, destroy your possessions, perhaps on occasion even soil something and these activities can go on for 20 years or more. So be strong, give yourself the opportunity to sleep on the decision and find the right kitten for you.
Doesn't change the aftermath of owning one, just keeps you at arms length from fluffy kitten mind control when you are making a long term commitment.