Use manual's figures - ~1.3 Vs - over the threshold (or just prior to it) & you won't go too far wrong. Remember Vs changes with weight. Allow some small additional amount IF there's gusts.
What speed you use on final is largely irrelevent as long as your speed is stable & correct at the threshold. I tend to fly fast down final with a speed reduction in the last 1/4 nm or so. Depends on the a/c type & its characteristics.