Boot Clock Randomization
The TimeSync page notes:
Using Boot Clock Randomization, i.e. after boot, the clock is set randomly between 0 and 180 seconds into the past or future. This is useful to enforce the design goal, that the host clock and Whonix-Workstation ™ clock should always slightly differ. It is also useful to obfuscate the clock when sdwdate itself is running, because naturally at this time, sdwdate hasn't finished. sdwdate runs after booting.
By randomly moving the system clock a few seconds (and nanseconds) in the past or future during boot, this enforces the design goal of a slightly different host clock and Gateway/Workstation clock, even before secure timesync has succeeded. This prevents time-based fingerprinting and linkability issues, thereby improving anonymity and privacy. 
Open /var/log/bootclockrandomization.log in an editor as a regular, non-root user.
- Notably, one recent change is the 0-5 second time window is no longer excluded in the process, as it was found to aid fingerprinting.