- activate the developer mode

- go to "Settings/Sequences & Identifiers/Sequences"

It will help you

override create function in model sale.order

from openerp import models 
import datetime 


class SaleOrder(models.Model):
    _inherit = 'sale.order' 

    def create(self, cr, uid, vals, context=None):
        if context is None: 
            context = {} 
        if vals.get('name', '/') == '/': 
            vals['name'] = self.pool.get('ir.sequence').get(cr, uid, 'sale.order', context=context) or '/' 
        # ================== ADDITIONAL LINES ================================================ 
        now = datetime.datetime.now() 
        vals['name'] = vals['name'].replace('SO', now.year) # GIVE YEAR FOR EXAMPLE
        # ==================================================================================== 
        if vals.get('partner_id') and any(f not in vals for f in ['partner_invoice_id', 'partner_shipping_id', 'pricelist_id', 'fiscal_position']): 
            defaults = self.onchange_partner_id(cr, uid, [], vals['partner_id'], context=context)['value'] 
            if not vals.get('fiscal_position') and vals.get('partner_shipping_id'): 
                delivery_onchange = self.onchange_delivery_id(cr, uid, [], vals.get('company_id'), None, vals['partner_id'], vals.get('partner_shipping_id'), context=context) 
                defaults.update(delivery_onchange['value']) 
            vals = dict(defaults, **vals) 
        ctx = dict(context or {}, mail_create_nolog=True) 
        new_id = super(sale_order, self).create(cr, uid, vals, context=ctx) 
        self.message_post(cr, uid, [new_id], body=_("Quotation created"), context=ctx) 
        return new_id