Short answer. At least three full calendar days before. The rule requires the parties to file with the court and serve on the adverse party their pre-trial briefs in such manner as shall ensure their receipt thereof at least three calendar days before the date of the pre-trial.
What the law says
in such manner as shall ensure their receipt thereof at least three calendar days before the date of the pre-trial
Rule 18, Section 6 — Pre. Read the full provision →
It is a receipt deadline, not just a mailing deadline
The rule does not simply require you to file or send the brief three days ahead — it requires the filing and service to be done in such manner as shall ensure their receipt at least three calendar days before the pre-trial date. That specific phrasing puts the entire focus on when the court and the adverse party actually receive the brief, not merely when you personally dispatched or sent it out on your end — a filing method that is fast but unreliable would not satisfy the rule if it fails to guarantee timely receipt.
Both the court and the opposing party get a copy
The obligation itself genuinely runs in two separate directions at once: you must file with the court and serve on the adverse party the pre-trial brief. Filing alone, without properly serving the other side, or serving the other side without also filing with the court, does not fully satisfy this requirement — both distinct steps are required within that same three-calendar-day window running up to pre-trial, and each one binds you separately regardless of whether the other was already accomplished.
What the brief itself has to contain
The rule expressly lists what the pre-trial brief must actually address, among other required things: a concise statement of the case and reliefs prayed for, a summary of admitted facts and proposed stipulations, the main factual and legal issues, the propriety of referring certain factual issues to commissioners, the evidence to be marked and its purpose, the witnesses and a summary of their testimony, and a brief statement of points of law together with proper citation of authorities.
Why the timing matters so much
Missing the timing requirement carries real weight: failure to file the pre-trial brief shall have the same effect as failure to appear at the pre-trial. That genuinely makes the three-calendar-day receipt deadline more than a mere formality — treating a late or missing brief the same way as an actual no-show is a genuinely serious consequence tied directly to missing this specific deadline, whatever the reason for the delay actually turns out to be.