Pretty much always the 1st and 15th. If either of those fall on a weekend or bank holiday then paid the nearest business day before. That sounds very annoying to not know what day you're getting paid.
I think getting paid every two weeks (eg every other Friday) is more common. This makes it easier for everyone to plan. Also how you get the payroll situation where every few years, people get an additional pay period [0].
Oh they let us know in advance. Anyway, being paid early isn't really a problem. If you're planning when outgoings should happen then you just need to plan on the contractual day, not assume that it will get there earlier. I think most larger companies usually pay on that same day but modulo weekends, so the last Thursday of the month or similar.
Especially +/- a whole week.