Mainly I notice prepositions at the end of a sentence when the preposition used is up, of, on, or at. ("Where is George at?" makes my teeth ache with the need to object.)

There's a large part of me that thinks "before" is no more a preposition than "prior". They're synonyms!

And now that I've thought that, I feel better about using it! Hah!

(will happily go on with my writing now...)