If my starter is still very active, with little sediment, I will pitch the whole thing. That usually is the case when I start my starter less than or around 24 hours before pitching. I will only do that if I have some fresh yeast, and I will keep the starter size to one quart. Those starters usually get rolling in a couple hours (VERY fresh yeast).
If I know I will brew and I have my yeast, I will start the starter a couple days earlier so that it finishes up in time for an overnight rest in the fridge. I like to cool it overnight to get better flocculation and also to give it time to warm back up for pitching. I will take the starter back out when I start heating my strike water.
TL