I doubt it will happen in a single day unless and until UNO is involved in it. Even though UNO can only make recommendations but can't force any country to adopt and make it legal. A country's government needs to be progressive to accept bitcoin. What Japan has done is remarkable and can't be done by all other countries at this point. Accepting a decentralised currency in to a strict centralised system, is a hell of a job. It won't happen anytime soon and definitely not on a single day.