I would maintain the soil as evenly moist as you can with no periods of dry soil, wet soil, dry soil again, etc. After that, you can fertilize if temps are not hot. But I do not recommend fertilizing them while stressed. Let alone using two fertilizers to wake them up. Holly-tone is usually very good and a slow-release fertilizer.
This year, my viburnums woke up early but I am so farther south than you... I would wait further before deciding to chop away dead wood. You can also do a scratch test carefully, using your finger nails to see if branches are still alive.