Opposite of unit delay is unit prediction and there is no way to predict a signal unless simulation is done up to that point. One way to implement this would be to simulate till the nth step and assume that to be the (n+1)th step and to consider the (n-1)th step as the nth step and so on. This way there is always a signal that acts like a future signal. You might have to reframe your implementation to accommodate this.
If you’re looking for an estimate, you can use estimators such as Kalman filter to predict future behavior.
