title_body: Calculate timestamp from slot
upvoted_answer: You did not account for Byron, where one slot was 20 seconds.
  To make it easier, take the start time of epoch 209 which is the Shelley hardfork and started at 1596491091 unix time on slot 4924800.
  Therefore to calculate the time of the current slot, you might try something like: 1596491091 + (current_slot - 4924800).