Najafi Q&A: Takbeeratul Ihram

When reciting the Takbir al-Ihram, does a person first open their mouth and then pronounce the Takbir, or does it begin when opening the mouth? Does the Takbir start at the opening of the mouth or at the utterance?

If the praying person does not pay attention to the Takbeer of Ihram (the Opening Takbir), would Allah keep the grace and reward away from the prayer?

It is mentioned in chapter five in Takbeeratul Ihram “it is a part of prayer which invalidates it if it is intentionally or unintentionally dropped off. Its increase invalidates the prayer. If you recite it again, the prayer is invalidated and you need to recite a third Takbeeratul Ihram. Reciting a fourth one invalidates the prayer, you will need the fifth, and so on it is invalidated in the even number and rectified in the odd number. The question is in what form the utterance “Allahu Akbar” is recited in that reciting the second invalidates the first? Is the first form of Allahu Akbar correct and the second is also correct, where the second invalidates the first, or is the form of Allahu Akbar incorrect and we recite the second one as correct to invalidate the first?