I am looking for a date to/for my opening tomorrow.
Note: Here “date” means “a person to go on a date with”. And “opening” means “the inauguration of a shop”.
Are both prepositions correct in the example? I believe “for” is appropriate here.
Only for is correct here.
For is used to mean "for the purpose of". To is usually used to mean "in the direction of" or as part of a verb phrase. You could use to if you wanted to phrase it like
I am looking for a date to take to my opening tomorrow.