QANTAS Planned fuel (not less than): 2500KG over destination. Most Guys in Good weather add 500kg - or plan to arrive with 3000 KG over head.
Plans for entire day are given at sign on - about 1hr before departure. Early am starts - the plans may have been prepared the night before by dispatch.
Plans can be easily redone if required - but usually adding fuel fixes most problems within reason.