Hello All,

I found this solution using re-define method of _get_prefix_suffix

def _get_prefix_suffix(self):
    def _interpolate(s, d):
        return (s % d) if s else ''

    def _interpolation_dict():
        now = range_date = effective_date = datetime.now(pytz.timezone(self._context.get('tz') or 'UTC'))
        if self._context.get('ir_sequence_date'):
            effective_date = fields.Datetime.from_string(self._context.get('ir_sequence_date'))
        if self._context.get('ir_sequence_date_range'):
            range_date = fields.Datetime.from_string(self._context.get('ir_sequence_date_range'))

        sequences = {
            'year': '%Y', 'month': '%m', 'day': '%d', 'y': '%y', 'doy': '%j', 'woy': '%W',
            'weekday': '%w', 'h24': '%H', 'h12': '%I', 'min': '%M', 'sec': '%S'
        }
        if range_date:
            ay = str(range_date.year)[2:] + '-' + \
                 str(range_date.year + 1)[2:]
            sequences.update({'ay': ay, 'month_text': '%B'})
        res = {}
        for key, format in sequences.items():
            res[key] = effective_date.strftime(format)
            res['range_' + key] = range_date.strftime(format)
            res['current_' + key] = now.strftime(format)

        return res

    d = _interpolation_dict()
    try:
        interpolated_prefix = _interpolate(self.prefix, d)
        interpolated_suffix = _interpolate(self.suffix, d)
    except ValueError:
        raise UserError(_('Invalid prefix or suffix for sequence \'%s\'') % (self.get('name')))
    return interpolated_prefix, interpolated_suffix

Then Go to 
Setting-->Technical-->Sequences&identifiers-->Sequence and search invoice.

Change Prefix to:  Inv/%(ay)s/%(month_text)s/

Appreciate to Mitul Shingala and OdooTools

Best Regards,

Ankit H Gandhi.

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