Damned if you do, damned if you don't situation. Too close to departure date and the good seats are all gone. Too far out, and risk losing the seat and the money paid.
Colleague has a knee injury so the extra legroom was a huge help heading out.

Thank you for the fine print. I do have a copy, and clearly read the non-transferable and non-refundable part, but one would hope (I won't say assume) that if it's the airline cancelling the flight and moving you to a new one, then they'd at least honour the seats paid!

To answer your last, 2-3 weeks out. Flights have been changed 4 times now