How to construct validation set for time series for NN? I would like to train my model with a validation set. As the data is a time series I have to use timeseriessplit:

import numpy as np    
from sklearn.model_selection import TimeSeriesSplit   
X = np.array([[1, 2], [3, 4], [1, 2], [3, 4], [1, 2], [3, 4]])    
y = np.array([1, 2, 3, 4, 5, 6])    
tscv = TimeSeriesSplit(n_splits=5)    
print(tscv)      
TimeSeriesSplit(max_train_size=None, n_splits=5)    
for train_index, test_index in tscv.split(X):    
...    print("TRAIN:", train_index, "TEST:", test_index)    
...    X_train, X_test = X[train_index], X[test_index]    
...    y_train, y_test = y[train_index], y[test_index]    
TRAIN: [0] TEST: [1]    
TRAIN: [0 1] TEST: [2]    
TRAIN: [0 1 2] TEST: [3]    
TRAIN: [0 1 2 3] TEST: [4]    
TRAIN: [0 1 2 3 4] TEST: [5]


Using this method, I obtain a train and test set.
But how can I generate a validation set now?
Im new to the topic too but I think the Idea is to create a Train/Test-Set and then take the TrainSet and Split it again in 2 Sets (mostly called Train and Development Set) for example with a KFold-CV. Train your model on the Train Set and improve it with the Developement Set. Then take the final model and use it on the whole trainingset.

The picture give you a clearer idea I think.