Bethesda announced on Twitter today that the new update, version 1.5.205, is now "live in preparation for mods." It also confirmed that the closed beta to test mods will begin next week.
Earlier in May, Bethesda said that it planned to bring mods to Xbox One in May following the release of the Far Harbor DLC, which launched this week. It also opened signups for the beta and said that those who are accepted will receive codes via email.
It didn't share any further details about what the beta will consist of or how long it will last. Mod support should also be on the way for PS4 in June.
While players have been using mods on PC since Fallout 4's launch in November, Bethesda only recently added official support for them.