Hi @Ivan welcome to the Atlassian Community forum and I wish you are staying safe.
To answer your query, the "original time estimation" for Next Gen is planned to roll out in the upcoming months: March, April, May.
Please access this Jira ticket being worked upon for including the feature:
https://jira.atlassian.com/browse/JSWCLOUD-17248
Alternatively, here is the documentation link for the steps you may check and follow:
https://support.atlassian.com/jira-software-cloud/docs/enable-estimation/
If my post addressed your query, kindly click "accept answer" for benefit of new members.
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