I have it already marked in my holiday planner for this year, the last weekend in September - ready for October 1 and the upcoming Canadian Thanksgiving (on the 9th this year).
Our local greenhouse has a 'fall porch package', a square bale of straw, mums and a bundle of dried corn stocks; makes it very easy! I also have scarecrows that we place in the mixed perennial beds beside the porch steps, pumpkins, the wreaths on the doors. I LOVE the fall mums - so I do purchase extra to place on the steps and tables.
(The straw bale is useful after its 'festive' use too in the garden, we use it to mulch the few flowers that may need some extra protection in the winter, and the birds love sitting on the corn stocks - we place it under the bird feeder in the garden for winter, composting in the spring.)