¿A qué hora?

We tend to think of cuando as the translation for when, but in a question it usually means what day rather than what time.

• ¿Cuándo llega? What day does he get here?
• ¿A qué horas llega? What time does he get here?

En la tarde

The question ¿A qué hora? sounds as if a specific hour is requested in the answer. However, it is common to give a vague response, such as en la tarde. It will be ready in the afternoon. Note that en la tarde usually means after the workday, that is, at 5:00pm, 6:00pm or 7:00pm. If you show up at one in the afternoon expecting your item to be ready, you're too early. La tarde can go all the way to dark, 8:00pm, although that general time of day is sometimes called tarde-noche.

• — ¿A qué hora pasas?
  — En la tarde-noche. Late afternoon, early evening.

Como a las cinco

To be noncommital, add a word like como.

• Como a las cinco. Around five o'clock.
• Te veo onda siete. See you around seven. Informal.
• Tipo nueve. Around nine o'clock. Informal.
• Alrededor de las dos. At about two o'clock. Somewhat formal.
• Aproximadamente a la una. A la una, aproximadamente. Around one o-clock. Formal. Recall that una is singular. Standard is es la una but I have heard son la una as well.