Does the first Friday Adhan (the Uthmani) occur before the time begins or after it?

The first Adhan for Jumu'ah is legislated, and this is what 'Uthman (may Allah be pleased with him) did and the Companions approved. It takes place half an hour or an hour before the time for Jumu'ah begins, to remind people and encourage them to prepare. The second Adhan is given when the Imam enters and sits on the minbar, announcing the entry of the prayer time. Some scholars believe that this timing is the most correct for achieving the benefit of the first Adhan in alerting people to get ready.