What is the right time to pay Zakat?

If you come across someone who deserves your Zakat, pay it to him right away. If you do not, then wait until you find someone. I always advise the listeners to check well for someone who deserves their Zakat and not just give their Zakat away to anyone, for someone might have a bad habit like smoking or the like, so he will spend the money on those bad habits. You should investigate, and you should know that the closest people to you are more entitled to your Zakat, whether they are close to you by blood, by poverty or by geography (like your neighbors).