I wouldn't place them anywhere toward the back of the tee pad. This may inhibit a run-up that isn't straight down the pad. If the tee signs are over 3ft high, You don't want to place them too close to the front sides of the tee pad. I've seen some signs placed too close that one could hit their hand on during follow-through.
Preferably, they should be placed 4-5ft from the front side of the tee pad.
However, I would evaluate each hole before making a decision.