Hello,

I think below link will helpful you.

http://blog.openerp4you.in/2013/04/how-to-create-scheduler-in-openerp.html

Thanks.

Shamji.

option 1: you can check/change it through settings page on 'Settings/Technical/Automation/Scheduled Actions', here you can adjust "Next Execution Date" and set time to the next 12 o'clock. 

option 2: you can add "nextcall" field directly in scheduled action record in XML, like this:

<field name="nextcall" eval="(DateTime.now() + timedelta(days=1)).strftime('%Y-%m-%d 12:00:00')" /> 

here '%Y-%m-%d 12:00:00' is midday in server time (server time may differ from your local time, but if you check at settings page, you'll see time in your local time). for midnight use '%Y-%m-%d 00:00:00',  i.e. 24 hours format.