diff --git a/mrp_production_date_planned_finished/models/mrp_production.py b/mrp_production_date_planned_finished/models/mrp_production.py
index 81e50b309..ecffdf680 100644
--- a/mrp_production_date_planned_finished/models/mrp_production.py
+++ b/mrp_production_date_planned_finished/models/mrp_production.py
@@ -10,12 +10,16 @@ from odoo import api, models
 class MrpProduction(models.Model):
     _inherit = "mrp.production"
 
+    def _get_date_planned_start_using_delays(self):
+        date_planned_start = self.date_planned_finished
+        date_planned_start -= relativedelta(days=self.product_id.produce_delay)
+        date_planned_start -= relativedelta(days=self.company_id.manufacturing_lead)
+        return date_planned_start
+
     @api.onchange("date_planned_finished")
     def _onchange_date_planned_finished_set_date_planned_start(self):
         if self.date_planned_finished and not self.is_planned:
-            date_planned_start = self.date_planned_finished
-            date_planned_start -= relativedelta(days=self.product_id.produce_delay)
-            date_planned_start -= relativedelta(days=self.company_id.manufacturing_lead)
+            date_planned_start = self._get_date_planned_start_using_delays()
             if date_planned_start == self.date_planned_finished:
                 date_planned_start -= relativedelta(hours=1)
             if self.date_planned_start != date_planned_start: