When do you feed your sourdough starter before you use it?

If I'm making bread, and my starter is active, I feed it that morning and in a couple hours at room temperature is usually enough. I just do a float test. You can use a starter straight from the fridge but you'll end up with a much more pronounced sour flavor in your bread, so I try not to do that. Higher temperatures promote more lactic (milk) acids in the starter which bring a sweeter, mildly sour (more French) flavor to bread....lower temperature promote more acetic (vinegar) acids in the starter. When I know I'm going to be making bread, I'll bring my starter out for a couple days to encourage those lactic acids. If your starter is healthy, active and it floats, it'll make bread, but it may not be bread you want.

My starter is going on 10 years old, so it's pretty sturdy. That said, I can put it directly into the pre-ferment and let that hang out at 75-80F for about 12 hrs, or until it's nice and bubbly, before making the final dough.
If the recipe doesn't call for a preferment, I will do a feed equal to the amount of starter needed in the final dough (thank you, baker's percentages!) and treat that similarly to a preferment.
My base starter seems to go dormant if it's more than a week since I've fed it, but it perks up when I whisk it with a fork to incorporate some air. I tend to feed it every few weeks.
If you save only a small amount of starter, you may want to do gradual builds in the days before baking so as to have enough starter to bake.
I think there are also individual variables, such as the strength of the yeasties, the type of flour you are feeding, and the temperature of your kitchen. Trust your instincts and your taste buds!
When I think of my great-grandfather, Franz, operating a village bakery in the days before electricity and gadgets, using a wood-fired hearth oven...I realize bread is pretty forgiving.