I can't think of a straightforward way to do this with AFNI commands. A very kludgey way would be to use 3dUndump and 3dTcat in a pretty complicated way Maybe someone else will have some idea here. Although it is relatively simple to add something like this, maybe to 3dTshift, we're pretty busy right now with a lot of other projects. It may be best to be clear on what kinds of input you would like for some future endeavor. 3D+time dataset, temporal offset volume (TR indices/time in seconds,milliseconds), number of output time points, TR-locked output,....