Hi Jieun,
Not sure if this is best practice but, I do this:
to3d -fim -prefix ${subj}-${study}-${run} -session $sess -time:zt $n_slices $tp $tr @${slicetimes} -assume_dicom_mosaic -@ < dimon.files.func${run}
The bit of note for you is:
-time:zt $n_slices $tp $tr @${slicetimes}
Where "slicetimes" is a text file containing a single column of acquisition times, one for each slice.
cheers
iain