diff --git a/app/models/procedure.rb b/app/models/procedure.rb
index 5da6426ad..126062de2 100644
--- a/app/models/procedure.rb
+++ b/app/models/procedure.rb
@@ -438,7 +438,15 @@ class Procedure < ApplicationRecord
   end
 
   def usual_traitement_time
-    percentile_time(:en_construction_at, :processed_at, 90)
+    times = Traitement.includes(:dossier)
+      .where(state: Dossier::TERMINE)
+      .where(processed_at: 1.month.ago..Time.zone.now)
+      .pluck('dossiers.en_construction_at', :processed_at)
+      .map { |(en_construction_at, processed_at)| processed_at - en_construction_at }
+
+    if times.present?
+      times.percentile(90).ceil
+    end
   end
 
   def populate_champ_stable_ids
@@ -610,18 +618,6 @@ class Procedure < ApplicationRecord
     end
   end
 
-  def percentile_time(start_attribute, end_attribute, p)
-    times = dossiers
-      .where.not(start_attribute => nil, end_attribute => nil)
-      .where(end_attribute => 1.month.ago..Time.zone.now)
-      .pluck(start_attribute, end_attribute)
-      .map { |(start_date, end_date)| end_date - start_date }
-
-    if times.present?
-      times.percentile(p).ceil
-    end
-  end
-
   def ensure_path_exists
     if self.path.blank?
       self.path = SecureRandom.uuid
diff --git a/spec/factories/dossier.rb b/spec/factories/dossier.rb
index 7abd373ea..51c2995e7 100644
--- a/spec/factories/dossier.rb
+++ b/spec/factories/dossier.rb
@@ -129,13 +129,21 @@ FactoryBot.define do
     trait :accepte do
       transient do
         motivation { nil }
+        processed_at { nil }
       end
 
       after(:create) do |dossier, evaluator|
         dossier.state = Dossier.states.fetch(:accepte)
-        dossier.en_construction_at ||= dossier.created_at + 1.minute
-        dossier.en_instruction_at ||= dossier.en_construction_at + 1.minute
-        dossier.traitements.build(state: Dossier.states.fetch(:accepte), processed_at: dossier.en_instruction_at + 1.minute, motivation: evaluator.motivation)
+        processed_at = evaluator.processed_at
+        if processed_at.present?
+          dossier.en_construction_at ||= processed_at - 2.minutes
+          dossier.en_instruction_at ||= processed_at - 1.minute
+          dossier.traitements.build(state: Dossier.states.fetch(:accepte), processed_at: processed_at, motivation: evaluator.motivation)
+        else
+          dossier.en_construction_at ||= dossier.created_at + 1.minute
+          dossier.en_instruction_at ||= dossier.en_construction_at + 1.minute
+          dossier.traitements.build(state: Dossier.states.fetch(:accepte), processed_at: dossier.en_instruction_at + 1.minute, motivation: evaluator.motivation)
+        end
         dossier.save!
       end
     end
diff --git a/spec/models/procedure_spec.rb b/spec/models/procedure_spec.rb
index 73c96c84b..6d4b5149f 100644
--- a/spec/models/procedure_spec.rb
+++ b/spec/models/procedure_spec.rb
@@ -958,8 +958,7 @@ describe Procedure do
     let(:procedure) { create(:procedure) }
 
     def create_dossier(construction_date:, instruction_date:, processed_date:)
-      dossier = create(:dossier, :accepte, procedure: procedure)
-      dossier.update!(en_construction_at: construction_date, en_instruction_at: instruction_date, processed_at: processed_date)
+      dossier = create(:dossier, :accepte, procedure: procedure, en_construction_at: construction_date, en_instruction_at: instruction_date, processed_at: processed_date)
     end
 
     before do