If you work behind the scenes in engineering, you will soon find out from the various vendors, however in the meantime have a look in MyBoeingFleet.
Sorry to say that you need to be accepting deliveries, from about line number 300 onwards and not 92 & 94.
For the money you are having to pay for them, you need the a/c to have a tech despatch level of 98% and above, plus an a/c that is near its proposed delivery weight.
What l have seen so far, l am glad Monarch did cancel its order, however Boeing & Rolls would have had a couple of more years to sort out the problems before ours were due.
As l said before, good luck, at least you will have a few months to get ready for long haul with them.