We use 'until' (or 'till' ) to say how long a situation continues:
- Shall we go now? No, let's wait until (or till ) it stops raining .
- I was tired this morning, so I stayed in bed until half past ten .
- Tom will be away until Monday , (so he'll come back on Monday)
- I'll be working until 11 o'clock , (so I'll stop working at 11 o'clock) (not 'by 11 o'clock')