"Not today, not tomorrow, but in two days!"
Translation:לא היום, לא מחר, אלא מחרתיים!
It's not correct, but you can say "לא היום, לא מחר, אלא בעוד יומיים"
As for using אבל here, it isn't quite right. It's as if you said in English "Not today, not tomorrow, however in two days!" - something feels missing in the sentence. In this example you have to use אלא.