For optimal growing, keep your bulbs in a cool (50-60 °F) spot, out of direct sunlight, for a couple of weeks until the roots have grown.
After this, put them in a bright warm spot. Some people recommend putting them under “grow lights,” or florescent lights. Or, if you want to speed up the flowering you can use a heat mat or heating pad underneath your bulbs.
Even if you don't have a cool place, narcissus will almost always bloom, they just might be a little leggy and less compact.
