When did Cleopatra VII begin her reign?

Technically Cleopatra began her reign in 51 BC upon the death of her father. However it was intended to be a co-rule between her and her brother Ptolemy XIII. They struggled for power with each one trying to push the other out. Cleopatra was exiled, and it was not until 47 BC, when Caesar arrived that Cleopatra was firmly established on the throne. Due to the power struggle events, Cleopatra did not have a solid grip on the throne until 47 BC.