The word 'scheduled' is a verb. Is it correct to say 'scheduled date'? In this phrase the word scheduled is used as an adjective. Date is when you meet someone who you are having romantic relationship with.
This is an acceptable use.
Scheduled in this context is the past participle form of the verb schedule. Participles have that name because they may "participate" in two different word classes simultaneously. Past participles, specifically, may act as adjectives, with a passive sense: a "scheduled date" is a date which has been scheduled.