The Emperor

You are the ruler of a medieval empire and you are about to throw a party tomorrow. This celebration is the most important you have ever hosted. You've got 1000 bottles of wine you have been planning to open for the celebration, but you find out that one of them is poisoned.

There appear no symptoms after somebody drinks the poison. Death occurs within ten to twenty hours after consuming even the smallest amount of poison.

You have over a thousand slaves at your disposal and just under 24 hours to determine which bottle is poisoned.

You have a handful of prisoners about to be executed, and it will ruin your party if anybody else get killed.

What is the smallest number of prisoners who have to drink your wine within next 24 hours to be absolutely sure that there is no more death threat to your guests?