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.
from __future__ import print_function
import json
import uuid
import time
import logging
import base64
import traceback
from six import iteritems
from flask import Flask, jsonify, request
from boto3.dynamodb.types import TypeDeserializer
from localstack.services import generic_proxy
from localstack.constants import TEST_AWS_ACCOUNT_ID
from localstack.utils.aws import aws_responses
from localstack.utils.common import short_uid, to_str
from localstack.utils.aws.aws_stack import (
    get_s3_client, firehose_stream_arn, connect_elasticsearch, extract_region_from_auth_header)
from localstack.utils.kinesis import kinesis_connector
from localstack.utils.analytics import event_publisher
APP_NAME = 'firehose_api'
app = Flask(APP_NAME)
ACTION_HEADER_PREFIX = 'Firehose_20150804'
LOG = logging.getLogger(__name__)
DELIVERY_STREAMS = {}
deser = TypeDeserializer()
def get_delivery_stream_names():