Many careers start at normal times. Business and journalism, around 11 (I could be wroong); music and film around 1 or 2 pm. Many end around 6 to 7 pm (except the criminals). Bars usually start around 11am; dance clubs around 5pm and lounges around 2pm.
I plan where my sim will go after work hours according to the time of bars, lounges and dance clubs. She sometimes hits one or two a night. Great way to meet people.