blown head gasket?

if you have a blown head gasket, woudl the car blow white smoke for a few seconds after u start it, or continuously? woudl someone who knows please reply quickly, because i am going to look at this car in a day. thank you

It would, most likely, be continuously. They may also either run like crap, or just have a slight power loss. Then eventually, the oil will turn milky. All engines, especially in the winter, will blow out steam for a while from condensation until they're completely warmed up. If the headgasket is blown, you'll also have bubbles under the radiator cap and the exhaust will have a sweet antifreeze smell to it.