There isn't a translation in the Cantonese dictionary. Is there a way to say "snap judgment" or the equivalent?
I don't think there is a Cantonese phrase equivalent to it. Usually we just use a sentence like "唔好咁快下结论" to express the idea of "Don't make a snap judgement".
It is a well-known saying for the 70s generation or earlier, but much less for the 80s generation and onwards.