open the chat and type /time set <number>. For example, /time set 0 would make it morning, and /time set 14000 would be night.
/time set 0
ex. /time set (time) ex. /time set day or /time set night
/time set day
/Time set 0
The command is: /time set day or /time set night. You can also use numbers (ex. /time set 15000, /time set 0, /time set 10000, etc.).
It is /time set [time] Replace [time] with: 0 for Day 14000 for Night
to change from day to night in minecraft without mods you have to wait until the sun goes down. to get from night to day you can right click a bed to sleep.
As of 1.3, commands were introduced to single-player. So, only if you have cheats enabled, issue the command: /time set night or /time set
You can set TNT off in Minecraft Beta by clicking it, or by triggering it with redstone.
Click t on your keyboard and write /time set night
With commands you can do /time set 14000 which makes it early night or something like 18000 for late night or anything in between. That's really the only way.
There is no release date set for it yet but it will most likely be some time next year.