diff -r 67d5653c0e7a trytond/trytond/modules/stock_supply/__init__.py
--- a/trytond/trytond/modules/stock_supply/__init__.py	Thu Jun 02 12:40:58 2016 +0200
+++ b/trytond/trytond/modules/stock_supply/__init__.py	Thu Jun 02 12:44:08 2016 +0200
@@ -13,6 +13,8 @@
     Pool.register(
         OrderPoint,
         Product,
+        ProductSupplier,
+        PurchaseConfiguration,
         PurchaseRequest,
         CreatePurchaseRequestStart,
         CreatePurchaseAskParty,
diff -r 67d5653c0e7a trytond/trytond/modules/stock_supply/product.py
--- a/trytond/trytond/modules/stock_supply/product.py	Thu Jun 02 12:40:58 2016 +0200
+++ b/trytond/trytond/modules/stock_supply/product.py	Thu Jun 02 12:44:08 2016 +0200
@@ -1,9 +1,9 @@
 #This file is part of Tryton.  The COPYRIGHT file at the top level of
 #this repository contains the full copyright notices and license terms.
 from trytond.model import fields
-from trytond.pool import PoolMeta
+from trytond.pool import Pool, PoolMeta
 
-__all__ = ['Product']
+__all__ = ['Product', 'ProductSupplier']
 __metaclass__ = PoolMeta
 
 
@@ -11,3 +11,15 @@
     __name__ = "product.product"
     order_points = fields.One2Many(
         'stock.order_point', 'product', 'Order Points')
+
+
+class ProductSupplier:
+    __metaclass__ = PoolMeta
+    __name__ = 'purchase.product_supplier'
+
+    def get_supply_period(self):
+        'Return the supply period for the purchase request in days'
+        pool = Pool()
+        Configuration = pool.get('purchase.configuration')
+        supply_period = Configuration(1).supply_period
+        return int(Configuration(1).supply_period) if supply_period else 1
diff -r 67d5653c0e7a trytond/trytond/modules/stock_supply/purchase_request.py
--- a/trytond/trytond/modules/stock_supply/purchase_request.py	Thu Jun 02 12:40:58 2016 +0200
+++ b/trytond/trytond/modules/stock_supply/purchase_request.py	Thu Jun 02 12:44:08 2016 +0200
@@ -10,10 +10,10 @@
     Button
 from trytond.pyson import If, In, Eval, Get
 from trytond.transaction import Transaction
-from trytond.pool import Pool
+from trytond.pool import Pool, PoolMeta
 from trytond.tools import grouped_slice
 
-__all__ = ['PurchaseRequest',
+__all__ = ['PurchaseRequest', 'PurchaseConfiguration',
     'CreatePurchaseRequestStart', 'CreatePurchaseRequest',
     'CreatePurchaseAskParty', 'CreatePurchase']
 
@@ -21,6 +21,17 @@
     'readonly': Eval('state') != 'draft',
     }
 DEPENDS = ['state']
+__metaclass__ = PoolMeta
+
+
+class PurchaseConfiguration:
+    __name__ = 'purchase.configuration'
+    supply_period = fields.Property(fields.Numeric('Supply Period',
+            help='In number of days', required=True))
+
+    @classmethod
+    def default_supply_period(cls):
+        return 1
 
 
 class PurchaseRequest(ModelSQL, ModelView):
@@ -326,9 +337,8 @@
 
         for product_supplier in product.product_suppliers:
             supply_date = product_supplier.compute_supply_date(date=today)
-            # TODO next_day is by default today + 1 but should depends
-            # on the CRON activity
-            next_day = today + datetime.timedelta(1)
+            next_day = today + datetime.timedelta(
+                product_supplier.get_supply_period())
             next_supply_date = product_supplier.compute_supply_date(
                 date=next_day)
             if (not min_date) or supply_date < min_date:
diff -r 67d5653c0e7a trytond/trytond/modules/stock_supply/purchase_request.xml
--- a/trytond/trytond/modules/stock_supply/purchase_request.xml	Thu Jun 02 12:40:58 2016 +0200
+++ b/trytond/trytond/modules/stock_supply/purchase_request.xml	Thu Jun 02 12:44:08 2016 +0200
@@ -3,6 +3,12 @@
 this repository contains the full copyright notices and license terms. -->
 <tryton>
     <data>
+        <record model="ir.ui.view" id="purchase_configuration_view_form">
+            <field name="model">purchase.configuration</field>
+            <field name="inherit"
+                ref="purchase.purchase_configuration_view_form"/>
+            <field name="name">purchase_configuration_form</field>
+        </record>
 
         <record model="res.group" id="group_purchase_request">
             <field name="name">Purchase Request</field>
diff -r 67d5653c0e7a trytond/trytond/modules/stock_supply/view/purchase_configuration_form.xml
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/trytond/trytond/modules/stock_supply/view/purchase_configuration_form.xml	Thu Jun 02 12:44:08 2016 +0200
@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
+this repository contains the full copyright notices and license terms. -->
+<data>
+    <xpath expr="/form/field[@name='purchase_invoice_method']"
+        position="after">
+        <label name="supply_period"/>
+        <field name="supply_period"/>
+    </xpath>
+</data>