When performing a Layered Finesse with a Lie Component, if the plan is to give a Fix Clue to the Finesse Target card (the "final" card that is to be blind-played), then it is important to wait until the last moment to give the Fix Clue. This is because after receiving the Fix Clue, the player will not play any more blind cards.
Thus, you should first wait for all of the "good" blind cards to play, and then give the Fix Clue to the Finesse Target, so that it comes "just in time" before the misplay.
Alternatively, if the plan is to give a Fix Clue to some other card than the Finesse Target (e.g. a number 5 clue to a 5 in the middle of the hand), then the Fix Clue does not necessarily have to be just in time. It can be done early, and the player will know that they have to continue blind-playing cards until they find the Finesse Target.