RadioBOSS calculates the estimated "Start Time" for each track in the playlist, but this time can be off for several seconds because of features that affect the track's playback time, namely:
1. Gap Killer removes silence at the beginning and end of the track. By default, this is calculated when the track is started. Until then, RadioBOSS doesn't "know" how much silence the track contains, and therefore the exact track duration is unknown.
2. Trigger Mix At in the Crossfade settings (menu Settings->Crossfades). When the MIX point is detected automatically, RadioBOSS is not able to calculate track playback time.
To make RadioBOSS calculate the Start Time precisely, the Trigger Mix At has to be turned off.
The Gap Killer should be turned off too. There's another way to trim the silence: scan tracks in advance.
1. Open Music Library (Tools -> Music Library)
2. Add your music to the library
3. Select all tracks in the list
4. Click Tools->Scan tracks and remove silence...
5. Click Start and wait until the operation completes.
6. Close Music Library (there's no need to save it).
When all tracks are scanned for the silence, RadioBOSS will be able to determine the exact track duration, and Start Time will be calculated precisely.
Note. When you add new music tracks, they need to be scanned the same way.