What word refers to how recent something is?
Solution 1:
I'd suggest currency. It works in a couple of ways, illustrated in the following definition:
currency noun
3. General acceptance or use; prevalence: the currency of a slang term.
4. The state of being current; up-to-dateness: Can you check the currency of this address?
TFD Online
Note that the main meaning for this noun involves money, which means that in certain circumstances its use may possibly necessitate a bit of disambiguation. But that shouldn't keep it from being used effectively.