(This was in the 80s/early 90s so none of the mechanisms are needed anymore)
The urgency of payment was handled implicitly by the banks. Salary payment was traditionally done using checks (back in those times, later bank transfer) where one would go personally to the employer's treasury, get a check, and absolutely had to go deposit that check on the same day or lose a non-trivial chunk to inflation. Settlement happened on the same day before midnight. (A system based on physical pieces of paper and signatures moved money faster in the 80's in Brazil than electronic bank transfers in Europe today.)
As for deciding what amount should be paid: there were rules to define by how much salaries would grow month after month, compensating for inflation, so it would even be possible to prepare the checks a few days before pay day. Inflation was high but the inflation rate wasn't that unpredictable month-to-month.
The urgency of payment was handled implicitly by the banks. Salary payment was traditionally done using checks (back in those times, later bank transfer) where one would go personally to the employer's treasury, get a check, and absolutely had to go deposit that check on the same day or lose a non-trivial chunk to inflation. Settlement happened on the same day before midnight. (A system based on physical pieces of paper and signatures moved money faster in the 80's in Brazil than electronic bank transfers in Europe today.)
As for deciding what amount should be paid: there were rules to define by how much salaries would grow month after month, compensating for inflation, so it would even be possible to prepare the checks a few days before pay day. Inflation was high but the inflation rate wasn't that unpredictable month-to-month.