There are designated times for lighting the Chanukah menorah: On Erev Shabbos we light before sunset (and before lighting Shabbos candles), and on Motzoei Shabbos we light after nightfall (after havdalah but before saying V’yiten Lecho). In shul, however, the menorah is lit before havdalah. On weekdays, it is preferable to light the menorah right after sunset. Beginning a half-hour before the time of the menorah lighting a person should not get involved in any other work in order to ensure that they light the menorah on time. If one is unable to light at the right time, there is room for leniency for lighting later, especially nowadays when we light indoors. In a situation where lighting at the appropriate time, or later, is not possible, there are poskim who are lenient and say that a person may light even before sunset, beginning at plag haminchah, although there is a question whether one may make a brachah it they light then. It may even be preferable to have someone else light on one’s behalf at the right time, rather than lighting so early. If a person must light before sunset, they should make certain that they use sufficient oil so that the menorah will burn until a half-hour after nightfall. If one needs to light late, they should try to light by midnight. If one is lighting late at night, especially when lighting after midnight, if there are other family members at home but they are all asleep, a brachah cannot be said. It is proper to wake them up, or at least some of them, and to light with a brachah.