Shifting Sequences Using MATLAB
In order to shift in MATLAB you need to play with the indices of the signal vector.
for example, given vector x - vX of length L, to shift it in time such that the first sample is the fifth you'll do this:

vXShifted = x(5:L);


Pay attention that the signal is shorter by 4 samples.

Now, sometimes, for periodic signals, a cyclic shifting is required which can be done using circshift() function in MATLAB.