This script converts your tweet archive to Day One entries. Tweets from the same day are grouped into the same entry.
First, you need Day One tha app, and its command line tool installed.
Assuming you unziped the tweet archive from Twitter at TWEETPATH, simply run:
python3 tweet_archive_to_dayone.py TWEETPATH/data/js/tweets/
Your method of running Python 3 environment may vary.