Chronos is completely allowed, but there is a difference between Kronos and Chronos. Let me explain:
Chronos; In Greek mythology, Chronos (Ancient Greek: Χρόνος) in pre-Socratic philosophical works is said to be the personification of time. AKA: Chronos is the god of time. He is by all means allowed.
Kronos; In Greek mythology, Cronus or Kronos (Ancient Greek: Κρόνος, Krónos) was the leader and the youngest of the first generation of Titans, divine descendants of Gaia, the earth, and Uranus, the sky. He overthrew his father and ruled during the mythological Golden Age, until he was overthrown by his own sons, Zeus, Hades, and Poseidon, and imprisoned in Tartarus. Cronus was usually depicted with a sickle or scythe, which was also the weapon he used to castrate and depose Uranus, his father. In Athens, on the twelfth day of the Attic month of Hekatombaion, a festival called Kronia was held in honor of Cronus to celebrate the harvest, suggesting that, as a result of his association with the virtuous Golden Age, Cronus continued to preside as a patron of harvest. Cronus was also identified in classical antiquity with the Roman deity Saturn. AKA: Kronos is the titan lord of time. He isn't allowed, but some Titans are, after going through the process.
I hope that answered your question!
Source: Wikipedia. (Normally, I wouldn't trust this site, but in this case, it all appears true.)