Distribution of timescales between the sub-millimetre peak (S_870, max) and subsequent quenching is shown for massive quiescent (MQ) progenitors (solid red histogram), and for faint (dark blue dashed), intermediate (purple dashed), and bright (orange dashed) dusty star-forming galaxies (DSFGs) selected at z = 3.4 (first panel), 4.3 (second panel), and 5.5 (third panel), the typical redshifts at which MQs at z = 2, 3, and 4, respectively, were in a DSFG phase. The timescale distributions for DSFGs exhibit similar peaks, although faint DSFGs show greater dispersion, with tails towards longer timescales. At z = 5.5, bright DSFGs present shorter timescales than their analogues at lower redshifts. MQ progenitors show systematically shorter timescales than DSFGs, with durations increasing for MQs selected at lower redshifts. A zoomed-in version of the MQ timescale distribution is shown in Figure B.1.