As per above, I NEVER remove shoes until after takeoff. Whilst the F QF pyjamas are moderately fashionable, I'd never be seen in public wearing the J pyjamas. So, incase of that 1:100000000 chance of an evacuation (or whatever the odds are), just wait until the seatbelt sign goes off before changing in the toilets (not in your seat - please (yes it does occasionally happen)). There's enough room in the side bins or overheads for your folded clothes (crew will only take jackets).