I find it depends on the show.

There’s some that use a set formula and you can tell if it’s your cup of tea pretty early.

For example:

X’s a cop but y’s…

The Devil

Immortal

A robot

A zombie

A serial killer

A cannibal

But some other shows might take longer to get into and figure out if they’re for you due to complexity or number of characters.

I think Sense8 or The Expanse would be a good example of that