On another note, Chartered A320, G-POWM has just been positioned as EXS061J from STN up to GLA. So it would seem that LS do not intend to cancel any lease, even with the addition of G-JZHD, unless the Privilege Style 757-200 is cancelled, which of course is unlikely.
Jet2holidays tend not to change flight times, as they aren't a charter airline like that of TOM, or TCX. That said, in that time, the aircraft config could have changed, so like LNIDA says, it wouldn't be advisable booking seats or airport car parking just yet. Anyone looking to book holidays should hold off a little - the release price tends to be higher than of that shortly afterwards.