The financial case for selling first is straightforward: no double mortgage payments, no double property tax bills under the City of Saskatoon's assessment cycle, and a known number in hand before you shop for your next place.
The case for selling after is about control: you avoid a rushed listing, you can fix up the home properly, and you set your own possession date rather than scrambling to match someone else's, though it usually means bridge financing or carrying two homes for a while.
There is no universally correct order, only the one that fits your actual finances and risk tolerance. Get your hand-reviewed valuation from Joel Dyck.