Is one who establishes the prayer without the knowledge of the Imam while he is performing ablution sinful?

The prayer is not to be established without the permission of the regular Imam. It is not permissible for anyone to lead the people in prayer without his permission, unless his delay is excessively long. And whoever presumes upon his authority is sinful. Al-Mardawi Al-Hanbali mentioned that this is forbidden. Furthermore, the time of the Iqamah (call to commence prayer) is up to the Imam. The muezzin should not establish the prayer except with his permission, and he should not establish it until the Imam is present and grants him permission to do so.