Hi,

You can try this code

Let us assume the field property is the given format

x_so_dispatch_date = fields.Date(string="Dispatch Date")

x_status = fields.Selection([('on_time', 'On Time'), ('late', 'Late')], string="Status")

then add the method like

@api.model

    def update_move_status(self):

        # Find moves that are not done and have a dispatch date after the current date

        late_moves = self.env['stock.move'].search([

            ('state', '!=', 'done'),

            ('x_so_dispatch_date', '>', fields.Date.today())

        ])

        # Update the status for late moves

        for move in late_moves:

            move.x_status = 'late'

        # Update the status for on-time moves

        on_time_moves = self.env['stock.move'].search([

            ('state', '!=', 'done'),

            ('x_so_dispatch_date', '        ])

        for move in on_time_moves:

            move.x_status = 'on_time'

Hope it helps

After fixing some indents errors and filed mismatchs i get the  "forbidden opcode(s) in 'lambda': STORE_ATTR" error on action save 
any idea why?

thank you 

class StockMove(models.Model):

    _inherit = 'stock.move'

    x_so_dispatch_date = fields.Date(string='Dispatch Date')

    x_status = fields.Selection([

        ('on_time', 'On Time'),

        ('late', 'Late'),

    ], string='Status', compute='_compute_status', store=True)

    def _compute_status(self):

        for move in self:

            if move.state != 'done' and move.x_so_dispatch_date:

                if move.x_so_dispatch_date > fields.Date.today():

                    move.x_status = 'on_time'

                else:

                    move.x_status = 'late'

            else:

                move.x_status = False