I usually make a one liter starter for a 5 gallon batch and two liter starter for 10 gallons. I make my starter a couple days before I brew and leave it on the stir plate at room temp until I'm ready to pitch. I have always followed Palmer's suggestion on making a starter. From his book, How to Brew Ch 6:
"Boil a pint (1/2 quart) of water and stir in 1/2 cup of DME. This will produce a starter of about 1.040 OG. Boil this for 10 minutes, adding a little bit of hops if you want to. Put the lid on the pan for the last couple minutes, turn off the stove and let it sit while you prepare for the next step. Adding a quarter teaspoon of yeast nutrient (vitamins, biotin, and dead yeast cells) to the starter wort is always advisable to ensure good growth..........Fill the kitchen sink with a couple inches of cold water. Take the covered pot and set it in the water, moving it around to speed the cooling. When the pot feels cool, about 80°F or less, pour the wort into a sanitized glass mason jar or something similar. Pour all of the wort in, even the sediment. This sediment consists of proteins and lipids which are actually beneficial for yeast growth at this stage. Ideally, the starter's temperature should be the same as what you plan the fermentation temperature to be. This allows the yeast to get acclimated to working at that temperature. If the yeast is started warmer and then pitched to a cooler fermentation environment, it may be shocked or stunned by the change in temperature and may take a couple days to regain normal activity."