Hiya! Additional input and examples are very welcome here, but just FYI, this is one of the most popular questions in this subreddit, so there are several previous threads that can get you started. Here are a few..

• FAQ section: How far back could I go and still communicate?

a few more recent interesting replies:

• How far back in time would you have to go before you could no longer understand spoken English? (I'm not talking about accents, but sentence structure, word usage, etc.) - featuring /u/qed1

• What's the furthest I could go back in time in, say, London and still generally understand the English being spoken? - featuring /u/jimthewanderer

• How far could I go back in time and still be able to understand period English and communicate effectively? - featuring /u/traininthedistance

if you have follow-up questions on locked posts, ask them here & tag the relevant user's username to notify them