Hello hanes teulu,
Basically, it depends on how fast she was travelling.
Its 5288 Nautical miles from Las Palmas, Grand Canaria to Cape Town. Assuming she only bunkered in Las Palmas and sailed the next day, if she was travelling at an economic speed of 15 knots. 15 days would be about right.
The only way to get a totally accurate figure is to consult pages 4 and 5 of the ships logbook. This will tell you to the minute what time she arrived and departed any particular port.
regards SW