Just wondering about cancelling now or later...

On May 21st I have a flight booked DOH-WAW in Economy (Q class both ways). Return on May 30th. I was to take a language course in WAW and then attend a conference. THEN, I was to fly back to DOH to work.

Today I received notice that the conference is cancelled and so is the language course. So, should I ask QR for a refund now or later? With a previous flight DOH-MCT, return, I received a travel voucher, but no refund. What are the chances of getting a full refund in $$ OR a travel voucher if I initiate the cancellation? Just wondering before I act/don't act.