Admissions decisions are made subject by subject, not collectively (as in the US). Sometimes a Department will batch them (so, wait until enough have come in and do them). A different one might scan them as they come in and pull the clear ‘yes’ or ‘no’ apps, respond to them, and set the ‘maybe’s’ aside until they see what else comes in. Another might stay on top of them and get them out as fast as they come in. There’s really no telling!
So far, CCers who have posted have heard from Modern + Art History, IR, and Management + French + Spanish.
You might keep an eye on this thread: http://talk.collegeconfidential.com/united-kingdom/2199834-st-andrews-american-applicants-class-of-2025.html#latest