dinesh_mareedu:

I am not able to know, what is called the time step in implementation time.


GRU (forward) behaves the the same (and as in the documentation you linked) between training and testing. The time step is the first dimension in the 3d input and output seq_len x batch x features. Maybe considering the (unit, use unsqueeze) batch size explicitly can help you (just in case you accidentally fed a single-time-step, 151 batch size into the GRU when you wanted 151 time step, batch size 1.
Best regards
Thomas