Yes - definitely tired of this polar vortex!
Another trick I've used if things don't seem to be happening is to make sure I
water with warm water - like 20C or so (70F).
Knowing the normal days to germination helps. I've had situations where the pots were past due and *nothing* had happened. I put them on the heat mat and the very next day I had sprouts.
Sometimes the issue is too cold at night, rather than too cold on "average". Since we heat with
wood and the plants are on a window-sill, they can get pretty cool overnight. You may find you can save some power by only turning on the heat mats overnight. A timer can help if remembering is a chore.