Here's how Amazon's TV hit fits into LoTR timeline.
'The Rings of Power' has established itself as a prequel to both 'The Lord of the Rings' and 'The Hobbit'. In this new original series produced by Amazon, its story is set centuries before when Tolkien's original novels take place. Yet its plot does not follow Middle-Earth's lore exactly. Leading to a complicated answer to the precise time period in which the show occurs. Here is a quick summary of the question, 'when is The Rings of Power set?'.
The constricted timeline
The reason for the show taking an unconventional approach to the setting of the series has to do with the sequence of events as noted by Tolkien when discussing the history of Middle-Earth. Throughout his books, and various commentaries discussed by Tolkien himself, there are specific details concerning the backstory of the novels that are considered canon in the LoTR universe. It is on these details that Amazon has based their original story on. Which will eventually meet the very beginning of the 'Hobbit' and 'Fellowship of the Ring.'
However, the dates and details as stated in the lore, take place over thousands of years. Something which does not fit easily within a televised series meant to tell that narrative in a faster, more continuous manner. To adapt this story more efficiently for audiences, the series decided to constrict the timing of events over a much shorter period. Developments that are supposed to take place over hundreds of years will instead appear to happen over months or days. It is because of this very considerable adaptation to the original source material, that it is complicated to assess exactly when the show takes place within the fictional universe.
An overview of the Second Age
What can be easily determined, is that the plot of the show will happen predominantly within the era of the Second Age. Middle-Earth's history is broken into a number of 'Ages' which span the length of time from Earth's initial creation. The world and the races which inhabit the locations of Middle-Earth appeared during the period of the First Age. Ending in the events of the downfall of Morgoth and the escape of Sauron. All events proceeding, take place in the Second Age, which is when the show's plot exists. The already familiar stories which involve the One Ring and the characters from the majority of Tolkien's novels all happen within the Third Age of Middle Earth.
The Second Age of Middle-Earth is said to last almost three and a half thousand years. The events that the show is based on therefore take place mostly around the years of SA. 1500. Which is when the rings of power are first forged. However, there are still many details that do not quite align with this date. The state of Numenor suggests that the events taking place are possibly set earlier into the Second Age period. Whereas the existence of characters such as Isildur, who isn't present until later (he isn't born until SA. 3209), suggests maybe the time period is later instead.
Maybe the exact setting of The Rings of Power should not be the central focus of the viewer's concentration at all. We can say with some certainty that it transpires within the very middle of Middle-Earth's history. And with most certainty that it is happening before the events of the books. Either way, there are at least three thousand years before Bilbo will be born. So maybe the exact date doesn't matter at all?