I would expect your camellia to have its buds in place already. Don't fleece until the weather is about to get bad and remove the fleece as soon as it warms up again.

Mine are showing signs of breaking already as I can see the pink petals showing but I don't think I can fleece it as its too big. I shall just have to leave it to chance.

I would leave it to take its chance during the winter. It is not a tender shrub/tree and do you really want to end up with loads of fleece-covered plants in your garden? Could it be that you might have lost the buds because they failed to set last year because the tree/shrub was allowed to get dry during the previous summer?

Or is it in an east facing border so gets the sun when still frosted?

Camellias often lose their flower buds over winter if they didn't get enough moisture during the previous summer. A bit late to cure this now! But worth remembering for next year.