For Kinesis, it seems to be, that AWS organizes its folders on S3 like: "prefix/2019/02/09/13/kinesis-stream-name-2019-02-09-10-02-32-db1db7a9-c484-40d1-b7ec-7651a55e4677"

The date in the path is UTC-time, the date in the file name is the UTC-time of the first received byte in the Kinesis stream for the specific file. This is the default behavior, so it would be nice to implement it in localstack.
streams = dynamodbstreams.list_streams()
        ddb_event_source_arn = None
        for stream in streams['Streams']:
            if stream['TableName'] == table_name:
                ddb_event_source_arn = stream['StreamArn']
        self.assertTrue(ddb_event_source_arn)
        
        zip_file = testutil.create_lambda_archive(load_file(TEST_LAMBDA_PYTHON), get_content=True,
            libs=TEST_LAMBDA_LIBS, runtime=LAMBDA_RUNTIME_PYTHON27)
        testutil.create_lambda_function(func_name=TEST_LAMBDA_NAME_DDB,
            zip_file=zip_file, event_source_arn=ddb_event_source_arn, runtime=LAMBDA_RUNTIME_PYTHON27, delete=True)
        
        assert_raises(Exception, testutil.create_lambda_function, func_name=TEST_LAMBDA_NAME_DDB,
            zip_file=zip_file, event_source_arn=ddb_event_source_arn, runtime=LAMBDA_RUNTIME_PYTHON27)
        
        kinesis_event_source_arn = kinesis.describe_stream(
            StreamName=TEST_LAMBDA_SOURCE_STREAM_NAME)['StreamDescription']['StreamARN']
        testutil.create_lambda_function(func_name=TEST_LAMBDA_NAME_STREAM,
            zip_file=zip_file, event_source_arn=kinesis_event_source_arn, runtime=LAMBDA_RUNTIME_PYTHON27)
        
        sqs_queue_info = testutil.create_sqs_queue(TEST_LAMBDA_NAME_QUEUE)
        testutil.create_lambda_function(func_name=TEST_LAMBDA_NAME_QUEUE,
            zip_file=zip_file, event_source_arn=sqs_queue_info['QueueArn'], runtime=LAMBDA_RUNTIME_PYTHON27)
        
        num_events_ddb = 15
        num_put_new_items = 5
        num_put_existing_items = 2
        num_batch_items = 3
        num_updates_ddb = num_events_ddb - num_put_new_items - num_put_existing_items - num_batch_items
        LOGGER.info('Putting %s items to table...' % num_events_ddb)