Enabling cheats in this version of Minecraft can be done at any time, and it is actually quite simple whether you are starting a new world or loading a game for a world that is already in progress.
Just like all the rest of Minecraft, using commands has gotten simpler and more accessible with each successive version. Instead of having to pore over lists of ID's for your enchanting commands ...
You can change game modes in "Minecraft" by using the "/gamemode" command, but you'll need to enable cheats first. You can use the /gamemode command in both ...