I'd give them a bit more time before cutting back......it could be unnecessary. By that I mean it is possible that these plants have suffered irreparable cold damage and should just be replaced. Typically, Schips have a die-off point of around 0F to -10. Anything lower than that for more than a day or two would certainly put them in harms way.

There's still some green so possibly some hope. If still alive and viable, you should see the shrubs pushing some new buds along the stems soon. That would be a good time to remove any browned or dead portions.

Thank you so much for your help.