diff -r e19cb8ea533a forecast.py
--- a/trytond/trytond/modules/stock_forecast/forecast.py	Wed Oct 30 13:23:56 2019 +0100
+++ b/trytond/trytond/modules/stock_forecast/forecast.py	Sat Nov 23 01:22:47 2019 +0100
@@ -448,15 +448,23 @@
                 unit_price, self.uom)
 
         moves = []
-        for day, qty in distribution.items():
-            if qty == 0.0:
+        pending = self.quantity - self.quantity_executed
+        for day in sorted(distribution.keys(), reverse=True):
+            qty = distribution[day]
+            quantity = qty * self.minimal_quantity
+            if day == 0:
+                quantity = max(quantity, pending)
+            else:
+                quantity = min(quantity, pending)
+            if quantity <= 0.0:
                 continue
+            pending -= quantity
             move = Move()
             move.from_location = self.forecast.warehouse.storage_location
             move.to_location = self.forecast.destination
             move.product = self.product
             move.uom = self.uom
-            move.quantity = qty * self.minimal_quantity
+            move.quantity = quantity
             move.planned_date = from_date + datetime.timedelta(day)
             move.company = self.forecast.company
             move.currency = self.forecast.company.currency