I want to use my Qatar Airways points to fly DOH-IST when is thebest deal?

Doha to Istanbul is one of the more interesting short-haul premium redemptions out there, and Qatar's own Privilege Club program is actually where you want to start. The sweet spot for that route in Business Class (Qsuite, if you're lucky enough to get it on the A350 operating that flight) sits in a reasonable range given the relatively short flight time, roughly two to three hours depending on routing. Privilege Club prices redemptions based on distance and cabin, so DOH-IST falls into a middle-tier zone that won't break your points bank the way a long-haul would.

The honest advice: check availability first, then worry about price. Qatar tends to release Qsuite availability on this route inconsistently, sometimes you'll find it wide open, other times it's cash-only or economy-only on award inventory. The best availability typically opens up either very close to departure (within two weeks, when they release unsold premium seats) or very far out (when the schedule first loads, usually 360 days in advance). That middle window of one to three months out is often the driest.

If you have Avios from British Airways or Iberia, that's also worth considering as a transfer route, Qatar is a oneworld partner and Avios price by distance, so a short hop like DOH-IST can be genuinely cheap in that system. Same goes for American AAdvantage miles, which can book Qatar Business at partner rates. Keep in mind that American's pricing for short oneworld partner flights can be a real bargain compared to what Privilege Club charges you for your own metal.

For timing in terms of actual travel, shoulder season on that route (spring and fall) tends to mean better award availability and a more pleasant Istanbul experience on arrival. July and August see heavy leisure demand into Istanbul and Qatar often fills those seats with cash passengers, making award space tighter. If you can be flexible and set up alerts through a tool like Point.me or Pointhound to track availability, you'll catch a seat when it drops rather than checking manually every day.