On Motzei Shabbos, some have the custom (as BTYA does) to daven Ma’ariv earlier than usual, to enable people to light neiros Chanuka as quickly as possible. One should not light, though, or do anything forbidden to do on Shabbos before the zeman he/she usually would do melacha on a Motzei Shabbos.
Care should be taken to at least say baruch hamavdil bein… before even just preparing for the lighting, or moving muktzah, and the like.
In order to avoid unnecessary delay, the Motzei Shabbos lights should be prepared to whatever degree possible on erev Shabbos.
The wife may say baruch hamavdil bein… when the zeman comes, and start the preparations before the husband is home from Shul.