We normally get the final zero fuel weight a few minutes after check-in closes - infact we cannot complete fuelling until we have the final ZFW - things are that tight . The final is rarely more than a ton adrift to the prediction at report time . The figures have already gone in as the tables move in steps of five tonnes and interpolation is rarely worth it .
The load sheet arrives by ACARS in its own sweet time and there is just the trim to set .