Adverbials can be placed in ...
I. "Seldom have I seen such a remarkable display of talent" is a grammatically correct example of inversion triggered by a negative adverb.
II. "Hardly had he arrived when the phone rang" demonstrates the correct use of inversion with a time-relationship adverbial.
III. "Little she knows about the surprise" is the correct emphatic form of the sentence "She knows little about the surprise".
It is correct what is stated