Setting a deadline tied to your actual moving date, rather than an open-ended one, is what usually gets the sorting done. Decades of belongings rarely get cleared by good intentions alone, and a fixed date creates the pressure that a vague one does not.
Items with real resale value, furniture, tools, collectibles, are worth handling separately from a general donation run, since selling them can offset moving costs. A local estate sale service or auction house can move a full house faster than listing pieces one at a time.
Joel Dyck can recommend Saskatoon estate sale and donation resources so the sorting does not become the reason the sale gets delayed. Get your hand-reviewed valuation from Joel Dyck.