What is the Time variable? If they are the effect estimates from multiple basis functions, use 3dMVM instead of 3dLME:
3dMVM \
-prefix HB.3dLME.INFUSE.2DXx3FILLx6TIME_wMeanFD.3x3x3 -jobs 8 \
-mask $standardMasksPath/avg152.3x3x3.wm.exclusion.mask+tlrc \
-model "GROUP+meanFD" -qVars "meanFD" \
-wsVars "FILL*TIME" \
...
Gang