You don't use "-stim_minlag" or "-stim_maxlag" with "-stim_times" ; these 2 options are for use with the alternative (and older) mechanism "-stim_file".
If you have 6 different stimulus classes (as your use of "-num_stimts" would indicate), then you need to have 6 different uses of "-stim_times" on the command line. You would separate the times for the different classes into different files. Then you could do
3dDeconvolve -input S1_all_runs+orig -nfirst 0 -nlast 495 -num_stimts 6 \
-stim_file 1 S1_trialA.1D GAM -stim_label 1 A \
-stim_file 2 S1_trialB.1D GAM -stim_label 1 B \
-stim_file 3 S1_trialC.1D GAM -stim_label 1 C \
-stim_file 4 S1_trialD.1D GAM -stim_label 1 D \
-stim_file 5 S1_trialE.1D GAM -stim_label 1 E \
-stim_file 6 S1_trialF.1D GAM -stim_label 1 F \
... (other options here to get some output, like -iresp) ...