Never

The coronation

The water bender spoke up, looking at the 3 nations below her. "Due to the war, we lost multiple innocent souls yet that doesn't mean work to sort that out will not be achieved. On my adventures with my friends I found out about the horrid things my family did, so now I'd like to introduce you to your new Fire Prince and Fire Princess." she said, signalling for the two Fire Nation siblings to come. "Also, on a much more serious note. The war is over and it is time we start a new era, an era where the nations will be treated equally. An era of love and peace." she says, then kneeling as someone says "All hail Chieftainess Katara!" and places the crown on her head. Everyone seemed so happy, a lot of people thanked her to which she was also happy about. Then as they sat on a bench there they had some tea, "So, first rule?" the new Chieftainess was asked. "There's multiple so I dunno to be honest with you." she replied. 

They all then went to bed, yet the water bender went to her brother's cell. "Sister?" he asked. She leaned into his cell, "Where is our father?" was her question. News had spread about their father's running away so who could blame her for asking that. "Far away." he replied. "Brother, I am giving you an opportunity to free your mind. Use it wisely." she then walked away. "He's hiding, most likely Whale Tail Island." he said. "Thank you Sokka." she said, smiling half mischievously half genuinely. Then they drank some more tea which was made by the Fire Nation siblings' uncle as the prince was trying to capture the moment in a painting. This art was not appreciated by everyone but the blind earth bender and the Avatar. Then the 13 year old boy walked outside to the balcony, swiftly followed by his girlfriend. "Hey." she said. "Hey." he replied. The two shared a kiss then the Fire Prince walked in on them and just said, "Ew oogies."