Does the time for prayer commence with the Adhan, or slightly before it? And is it permissible for someone afflicted with urinary incontinence to perform ablution five minutes before the Adhan in order to catch the congregational prayer?

The legally recognized method for determining prayer times is through the cosmic signs that the Sacred Law has specified for each prayer. The entry of a prayer's time does not mean the adhan (call to prayer) has been made, but rather the presence of the legal sign. Usually, the muezzins call the adhan when the time has entered.

For a person afflicted with urinary incontinence (sahib al-salas), they should perform wudu (ablution) for each prayer after its time has begun. If they perform wudu before the time has begun and nothing from their continuous impurity exits, their wudu is valid according to some scholars.

If the entry of the time is confirmed or highly probable, it is permissible to perform wudu at home and go to the mosque, even if the adhan has not been heard. And if one performs wudu a few minutes before hearing the adhan and their wudu is not nullified, it is valid according to some scholars, and this is the view preferred by Sheikh Ibn 'Uthaymeen.