DON'T REFUND NOW!

Wait until the last possible date.

If you are going to get back almost no money you might gain from the following circumstances:

BA cancel or re-time the flight. So you then you get a free rebooking!

There is horrendous weather - like today - and so flight is cancelled. So you then get a free rebooking!

(good chance of the first if you booked a long time ago. I just cancelled - and had all my money refunded including phone booking fee and cancellation fee waived - a SJU-MIA-PTY avios ticket. No time changes, but AA changed flight numbers! Good enough for me!)

I also cancelled and got full refund on an Iberia PTY-MAD avios ticket - IB changed flight times by 20 minutes!

Rebooking will then give you much longer validity!