NASA current target is late 2030's/early 2040's. I think there likely to be some delays as there usually are so my guess would be mid 2040's /late 2040's. This is a assuming between now and then we don't get a president that for what ever reason anti NASA and cut the program.
A very brief summary of plan
The very early plan is for them to go and come back so not a one way trip as some other people in this thread suggested. As for supplies the plans call for dropping off 25 tons of supplies using unmanned missions too mars before the astronauts are sent so enough supplies for there time on the planet and for the return trip. 2 people would always remain in orbit over mars and 2 would be on surface. they would have a vehicle to take them back and forth from surface to there ship in orbit. A vehicle on the ship to get to surface and a vehicle that waiting for them on surface that was delivered on one of the unmanned missions.
A article with a brief summary of the plan I typed above
https://www.space.com/nasa-plans-astronauts-mars-mission-30-days
and for the complete briefing that NASA gave
https://www.youtube.com/watch?v=Kd4nmO222i8&ab_channel=NASAVideo







