Formal:
* Quand j'ai terminé: This is the most literal translation and is appropriate in formal settings.
* Lorsque j'ai fini: This is another formal option, meaning "when I finished".
Informal:
* Quand j'ai fini: This is the informal equivalent of "quand j'ai terminé".
* Une fois que j'ai fini: This means "once I finished" and is a bit more casual.
Other options:
* Après avoir terminé: This means "after having finished" and is a more formal way to express the same idea.
* Dès que j'ai terminé: This means "as soon as I finished" and emphasizes the immediacy of the action.
The best option will depend on the context of your sentence. For example, you might use "quand j'ai terminé" in a formal report, while you might use "une fois que j'ai fini" in a conversation with a friend.