When and where did Norbert get ordered to be sent to Romania?

Norbert was initially living with Hagrid in his hut (pg. 188). After Charlie agreed to take him, raise him, and set him free, Hagrid eventually agreed to let him go. Norbert was officially picked up by four of Charlie's friends on broomsticks.

"Bye-bye, Norbert!" Hagrid sobbed, as Harry and Hermione covered the crate with the invisibility cloak and stepped underneath it themselves. "Mommy will never forget you!" (pg. 192)

Charlie's friends were a cheery lot. They showed Harry and Hermione the harness they'd rigged up, so they could suspend Norbert between them. They all helped buckle Norbert safely into it and then Harry and Hermione shook hands with the others and thanked them very much.

At last, Norbert was going... going... gone. (pg. 193)