I'm not sure Jon is right on this occasion.
What's the point in being in perfect rhythm, if they haven't even learned the correct sequence yet?
I think Nush re-read Big Brother's instructions with the task and they said that the housemates had been given the handbells and chart first so that they could practice the order of the notes. They would then be given a metronome later on to give them an idea of the correct rhythm to play along to.
'Don't run before you can walk' springs to mind!
Chill out a bit Jon - you've got another 3 days to practice yet!