Make sure the screws are long enough to get though the nut plates. You can slightly squeeze the aft part of the nut plates to firm up the locking feature until they can be replaced.
Are you using tinnermans under the screws? I assume you are.
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”