I find a tip I got from Don Schoenholt useful. After you've swallowed or spat, chew and swallow a few times. This forces the aromas from the remaining coffee coating your palate into the retronasal cavity. The resulting taste effect is scored as the coffee's finish.

After taking the Q-course, I can, somewhat ruefully, confirm what every experienced cupper says: first impressions are by far the most accurate. If you aren't certain from the first quick taste, take a long break and get another fast impression. This means not making a too big production out of getting the finish and the retronasal aromas, do it quickly, and take whatever that first impression gives you.

Flint, it's usual to cup between 8 and 24 hours after roasting; waiting almost never improves things. If the coffee is fermented or otherwise funky, it may get better with time, but only if its going from bad to not so bad. There is no point drinking bad coffee, just dump it.

Note:ferment that tastes good right off the bat, for instance, like overripe fruit and alcohol, is OK by me; but may not be for you. On the other hand, ferment that "improves" is almost never worth the trouble.

Will, I'm sorry, somehow your post slipped between the cracks:

When you have a bean you intend only for espresso, do your cupping roast a few degrees darker than a classic cupping roast, so you can taste some roast flavors. How dark you'll go for the espresso will depend on how good they are.

But even with this, the roast depth of your first espresso roast will be more an educated guess. The kind of bean, especially if you've had it before, is usually a big factor. The cupping result will tell you if this coffee is typical of the ones you had before, or whether there's something that needs special handling. Experience and the cupping outcome together will make for a pretty good first guess.