So...what's your question..., if you want a Japanese translation for "One day I will look like an elephant... I can't wait!", then I might write it as "そのうちゾウみたいになっちゃうよ・・・たのしみ！" (But I may be misreading your sentences cos I'm not sure what you mean by saying you can't wait to look like an elephant...)
Thanks... A Japanese friend and I always joke around... I put a photo of me eating ice cream on facebook, and she wrote, " "そんなにでっかいアイスたべちゃ、どんどん太っちゃうよ!!!" I want to respond sarcastically, "One day I will look like an elephant... I can't wait!" In other words, one day I will be big and fat like an elephant... I can't wait!
Thanks for the feedback, haha alright then I think you could say like 'いつか、ゾウさんみたいにおおきくなるんだよ・・・たのしみ！' or more casually 'いつかゾウさんみたいにおっきくなるんだ・・・たのしみだよ!'/'いつかゾウさんみたいにでっかくなるんだもんね~...たのしみだね~!' (Of course you can simply say 'ゾウ' instead of 'ゾウさん' to refer to an elephant. Adding 'さん' just makes it sound cuter.)