FayeÂ Johnson has said theÂ shamed ex-Sunderland starÂ would be out of HMP Moorland in six months after he was caged for six years in March 2016.
Posting a snap of her son on Twitter in his school uniform, she said: "I remember 2 and a half years ago I said that @lucas11johnoÂ would be in year 3 when @a.johnson came home!
"I now have a year 3 child and the count down is on till my brother is home.
"6 months to go."
She has stood by her brother since he was jailed and also campaigned to get his conviction overturned.
He hasÂ launched unsuccessful appeals against his conviction and isÂ eligible for release in March next year.
He was jailed after being convicted of engaging in sexual activity with a besotted 15-year-old fan.
The court heard Johnson met his victim when she was just 14 and soon began grooming her online, despite knowing she was 15, before meeting her twice in his Â£80,000 Range Rover.
On the second occasion, they engaged in sexual activity just three weeks after hisÂ ex Stacey FloundersÂ gave birth to their daughter Ayla.