Lemon, as common as it is, is quite a sublimely beautiful scent. When you ask someone to describe the scent, they almost always say, "Citrusy" or "Lemony", or if you've got a real joker on your hands, "Furniture polish!".
Cold-pressed lemon oil, as a perfumery ingredient, is much more complex than any of these descriptions, running the gamut between aldehydic notes that are sweet-fruity-floral, to notes that go all musty and old paperish and take on a powdered lemonade scent.
The time it takes for lemon oil essence to move from its most-loved (in my opinion), and most recognized, fruity-tart-sharp-cool notes to musty-crackling old paper is a matter of minutes. The old paper scent remains for hours, though. Then it's gone.