It is "Yo administro bien mi tiempo". I'd say it that way. :)

I'd say "Me organizo bien". This would include time too. If you want to be more specific you can say "Organizo bien mi tiempo", "Gestiono bien mi tiempo". "Administro bien mi tiempo" and "Manejo bien mi tiempo" are correct too. Depending on where you are, you will hear different ones.

I think, it could be "Yo manejo bien mi tiempo" too