1 or 2 days
Crescent, waning
You would have to wait until after the moon is full. Then, the moon is in its waning phase and you can see it!
To determine if a crescent moon is waxing or waning, look at the shape of the illuminated side. If the illuminated side is on the right, it is waxing (getting bigger). If the illuminated side is on the left, it is waning (getting smaller).
A gibbous moon (waxing or waning) is when we can see morethan half of the moon's sunlit side when viewed from Earth, a gibbous moon has a sort of lemon shape. A crescent moon (waxing or waning) is when we can see less than half of the moon's sunlit side and it looks like a fingernail when viewed from Earth.
In a typical month, you can see two crescent moons: one during the waxing phase and one during the waning phase. The waxing crescent appears shortly after the new moon, while the waning crescent appears just before the new moon again. Depending on the lunar cycle, there may be slight variations, but generally, two crescent moons are visible each month.
The size of the moon doesn't change, but the amount of its illuminated half that we see does change. "Crescent" is the shape of less than a half-disk. "Gibbous" is the shape of more than a half-disk but less than a full disk. So the gibbous is larger than the crescent, whether waxing or waning.
The moon passed Third Quarter and became a waning crescent on November 28, 2010. Any time you're able to see it after than ... until the moment of New Moon at around 4 AM Central Time on December 5 ... you see a waning crescent.
Those are called the "phases" of the Moon. The Moon can be "full", meaning we can see all of the sunlit hemisphere. It can be "new", meaning we can't see any of it in sunlight. Between those phases are "waxing and waning crescents" and "waxing and waning gibbous", and the "first and third quarter phases". The actual order of the phases is: New, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, third quarter, waning crescent.
here is the order of the phases: New Moon Waxing Crescent First Quarter Waxing Gibbous Full Moon Waning Gibbous Third Quarter Waning Crescent.... and over again
Crescent.
The phases of the moon are determined by how much of the illuminated half of the Moon can be observed from Earth (from which only one face is visible). Beginning with the New Moon, when the Moon is directly between the Earth and the Sun, the phases are:New moon (0% illuminated)Waxing crescent moon (1% to 49%)First quarter moon (50%)Waxing gibbous moon (51% to 99%)Full moon (100%)Waning gibbous moon (99% to 51%)Last quarter moon (50%)Waning crescent moon (49% to 1%)(and back to New)(See the related links below for more information including a pictorial.)
On Earth, someone would most likely see less then half of a moon.