Chandra Darshan is the first day of moon finding after no moon day. In Hinduism, the new moon day is known as Amavasya and the first finding of moon after new moon has devout import.
People observe a day long fast and break it after sighting new moon on Chandra Darshan day.
Predicting the first day of Chandra Darshan is always a testing task for Panchang makers. The moon is observable only for a short span of time on the first day of Chandra Darshan and that is just after the sunset.
In other words, the moon sets about one hour after sunset and can be sighted only after sunset due to person in the same possibility as that of the sun. Hence the moon can be sighted only after the sunset, when it is also going to be set.