Right point in workflow to scale the features

DO NOT SCALE FEATURES AND THEN SPLIT INTO TRAIN AND TEST. THIS WILL CAUSE DATA LEAKAGE.

Scale the features on the train set. Use the same scalar object to Scale the features on Test set.

Don’t rebuild the scaler on the test set. This will Scale the test set on a different distribution than on what the model will trained on. As a result there will be a bias in predictions.