The body discovery announcement in Roblox Carnage appears to be the cue that starts the investigation phase, and one wiki entry notes that trials follow once a body has been discovered. A fan wiki also mentions a body discovery cutscene/update, but I couldn’t verify a fixed duration for the BDA itself from the available source material.

What that means

  • The BDA is basically the body discovery announcement.
  • It seems to be tied to a discovery cutscene/trigger rather than a long gameplay event.
  • The exact length is not stated in the sources I found.

Practical answer

If you’re asking “how long does it take,” the safest answer is: it seems short, likely just a brief cutscene/announcement, not a lengthy sequence.

TL;DR

No confirmed exact time showed up in the sources I found; the BDA in Carnage looks like a short body-discovery cutscene/announcement that leads into trials.