I'm a little new to Q (got red pilled after the stolen election). How do the Delta's work, I have understood a 1 year delta means that the Q post is relevant to the same date a year later, but how do we know which year is relevant?

Are there some Q posts that have specific delta's like a 1 year, 2 year, 3 year delta? Or can a post be relevant in any of the following years and we don't know yet which year it will be?