NAR - How can I make a prediction more spaced?

Hello,

I am using TDNN (NAR - Nonlinear Autoregressive). An simple example is presented below.

I am using 25 hidden neurons and the number of delays is equals to 8. The NN is working quite well to forecast y(t). However, I would like to forecast y(t+12) and y(t+24).

Is it possible to choose the time step that I intend to forecast in this present formulation?

Regards

  clc; clear all;close all
    
    % input 
    t2 = linspace(0,20*pi,500); 
    y  = sin(t2) + sin(0.25*t2); 
    
    % convert
    T = tonndata(y,true,false);
    
    trainFcn = 'trainlm';  % Levenberg-Marquardt backpropagation.
    
    % Create a Nonlinear Autoregressive Network
    feedbackDelays = 1:8;
    hiddenLayerSize = 25;
    net = narnet(feedbackDelays,hiddenLayerSize,'open',trainFcn);
    
    % numbers of delays, with open loop or closed loop feedback modes.
    [x,xi,ai,t] = preparets(net,{},{},T);
    
    % Setup Division of Data for Training, Validation, Testing
    net.divideParam.trainRatio = 70/100;
    net.divideParam.valRatio = 15/100;
    net.divideParam.testRatio = 15/100;
    
    % Train the Network
    [net,tr] = train(net,x,t,xi,ai);
    
    % Test the Network
    y = net(x,xi,ai);
    e = gsubtract(t,y);
    performance = perform(net,t,y);
    
    % Forecast Data 
    THAT = linspace(20*pi,100*pi,2500);
    YHAT = sin(THAT) + sin(0.25*THAT);
    
    % coverter double - cell 
    YHAT = con2seq(YHAT);
    
    % Forecast 
    YHAT = net(YHAT,xi,ai);
    
    % converter cell - double (plotar)
    YHAT = cell2mat(YHAT);
    
    figure
    THAT = linspace(20*pi,100*pi,2500);
    yhat = sin(THAT)+ sin(0.25*THAT);
    hold on
    plot(THAT,YHAT,'--o')
    %plot(THAT,yhat,':r');
    
    % %
    yz = sin(t2) + sin(0.25*t2);
     plot(t2,yz,'--r')
    
    legend('Forecast','training')