diff --git a/CHANGELOG b/CHANGELOG
index 68a43e5dd7..33d6449d22 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,6 @@
+* Use SQL CurrentTimestamp to fill numbered_at
+* Rename open_date into numbered_at
+
 Version 5.2.0 - 2019-05-06
 * Bug fixes (see mercurial logs for details)
 * Add history on payment term line delta
diff --git a/account.py b/account.py
index ae0fbd3d3a..d238458290 100644
--- a/account.py
+++ b/account.py
@@ -1,37 +1,53 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
-import datetime
+from sql.functions import CurrentTimestamp
 
 from trytond.model import ModelView, Workflow, fields
 from trytond.pool import PoolMeta
+from trytond.transaction import Transaction
 
 __all__ = ['Invoice']
 
 
 class Invoice(metaclass=PoolMeta):
     __name__ = 'account.invoice'
-    open_date = fields.Timestamp('Open Date')
+    numbered_at = fields.Timestamp("Numbered At")
+
+    @classmethod
+    def __register__(cls, module_name):
+        super().__register__(module_name)
+        table_h = cls.__table_handler__(module_name)
+        table = cls.__table__()
+        cursor = Transaction().connection.cursor()
+
+        # Migration from 5.2: rename open_date into numbered_at
+        if table_h.column_exist('open_date'):
+            cursor.execute(
+                *table.update(
+                    [table.numbered_at],
+                    [table.open_date]))
+            table_h.drop_column('open_date')
 
     @classmethod
     def __setup__(cls):
         super(Invoice, cls).__setup__()
-        cls.party.datetime_field = 'open_date'
-        if 'open_date' not in cls.party.depends:
-            cls.party.depends.append('open_date')
-        cls.invoice_address.datetime_field = 'open_date'
-        if 'open_date' not in cls.invoice_address.depends:
-            cls.invoice_address.depends.append('open_date')
-        cls.payment_term.datetime_field = 'open_date'
-        if 'open_date' not in cls.payment_term.depends:
-            cls.payment_term.depends.append('open_date')
+        cls.party.datetime_field = 'numbered_at'
+        if 'numbered_at' not in cls.party.depends:
+            cls.party.depends.append('numbered_at')
+        cls.invoice_address.datetime_field = 'numbered_at'
+        if 'numbered_at' not in cls.invoice_address.depends:
+            cls.invoice_address.depends.append('numbered_at')
+        cls.payment_term.datetime_field = 'numbered_at'
+        if 'numbered_at' not in cls.payment_term.depends:
+            cls.payment_term.depends.append('numbered_at')
 
     @classmethod
     def set_number(cls, invoices):
-        set_open_date = [i for i in invoices if not i.number]
+        numbered = [i for i in invoices if not i.number or not i.numbered_at]
         super(Invoice, cls).set_number(invoices)
-        if set_open_date:
-            cls.write(set_open_date, {
-                    'open_date': datetime.datetime.now(),
+        if numbered:
+            cls.write(numbered, {
+                    'numbered_at': CurrentTimestamp(),
                     })
 
     @classmethod
@@ -40,7 +56,7 @@ class Invoice(metaclass=PoolMeta):
     def draft(cls, invoices):
         super(Invoice, cls).draft(invoices)
         cls.write(invoices, {
-                'open_date': None,
+                'numbered_at': None,
                 })
 
     @classmethod
@@ -49,5 +65,5 @@ class Invoice(metaclass=PoolMeta):
             default = {}
         else:
             default = default.copy()
-        default.setdefault('open_date', None)
+        default.setdefault('numbered_at', None)
         return super(Invoice, cls).copy(invoices, default=default)