When are we going to return to the Moon?

This question is a bit unclear, because it doesn't specify if returning to the Moon means a manned mission to the Moon's surface, a manned Moon orbital mission, or an unmanned mission to the Moon.  
If the question is asking about a manned mission to the lunar surface, then there is no definitive date.  The only countries that currently have a public declaration of a possible manned mission to the lunar surface are China and Russia.  Those are "tentative proposals," and the stated date is sometime in the 2030's.  
China has some definite plans to return to the Moon, but those missions are unmanned missions.  Chang'e 4 is scheduled to launch in 2018 and land on the far side of the Moon. Chang'e 5 was scheduled to launch in late 2017, but it is now slotted for a 2019 departure.  It will land on the Moon, collect samples, and return to Earth. This will be the first lunar sample return mission since 1976.
Currently, NASA is trying get humans on Mars.  While NASA has no current plans to land humans on the moon, NASA is looking at a lunar orbit as a possible staging ground for future Mars missions.  According to Space.com, "a group of astronauts may spend a year in orbit around the moon in the late 2020's as part of NASA's plan to send humans to Mars in the 2030's."
https://nssdc.gsfc.nasa.gov/planetary/lunar/cnsa_moon_future.html

https://www.iflscience.com/space/heres-a-list-of-every-upcoming-space-mission-for-the-next-twenty-years-and-some-of-them-are-unbelievably-awesome/all/

https://www.space.com/36781-nasa-yearlong-crew-moon-mission-ahead-of-mars.html