The next few months would be marketing prowess by Jio and Airtel - who is first to launch.
Airtel will launch 5G in a city or probably on a few of their Towers and claim that they have launched 5G in that particular state. The same happened with 4G. It'll all be marketing atleast in 2021.
As per news..airtel tested 5g on thier 4g bands since 5g spectrum isnt out yet.So yeah they can commercially give out 5g speed on 4g bands just with a software update to all towers within months. But airtel head told they will be rolling out only when 5g spectrum is given.