Some things to keep your house warm in these shoulder months.

Open *all* curtains, blinds, shutters, etc.
Open some windows when it is warmer outside than in.
If it isn't humid in the house, try avoiding use of bath and kitchen fans.
Leave the water in the tub after a bath or shower, until it is cold.
Cook. Now is the time to make jam, baked goods (to be frozen), chicken pot pies (ditto)...

Insulate, and air seal the place, add interior storm windows. I don't expect to need *any* heat for another month.