It is permissible to have the intention of praying at the same time as the opening takbeer or before it
Question

                Is it better to make intention simultaneously with articulatulating the opening Takbeer or can it be made before? What is the view of ulamaa on this matter? I have read the previous answers، but this really gives me a hard time during prayers.
Praise be to Allah.
    The intention (niyyah) is a condition of the prayer being 
    valid, and the prayer is not valid without the intention, because the 
    Prophet (blessings and peace of Allah be upon him) said: “Actions are but by 
    intention, and each person will have but that which he intended.” What is 
    meant by intention is resolve, and its place is in the heart.

    End quote from al-Mughni, 1/287 

    The intention may accompany the opening takbeer, or it may 
    come before it. 

    Some scholars even said that there may be a long time between 
    the intention and the prayer, so long as the intention is not cancelled. 

    See: al-Mawsoo‘ah al-Fiqhiyyah, 13/219 

    Al-Mardaawi said in al-Insaaf (2/23): 

    Others said: there may be a long time in between, so long as 
    it (the intention) is not cancelled. Abu Taalib and others narrated (i.e., 
    from Imam Ahmad): If he goes out of his house intending to pray, then this 
    is the intention. Do you think that he would say the (opening) takbeer 
    without intending to pray? 

    This is what is implied by the words of al-Khuraqi and it is 
    the view favoured by al-Aamidi and Shaykh Taqi al-Deen in Sharh al-‘Umdah. 
    End quote. 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: 

    This opinion is more correct, because his intention is 
    accompanied by the ruling, so long as he does not intend to cancel it. When 
    the adhaan is given, if this man does wudoo’ for prayer, then the intention 
    escapes his mind, then when the iqaamah is given for prayer he starts to 
    pray without forming a new intention, his prayer is valid because he did not 
    cancel the first intention. So the ruling on it is still connected to the 
    action because of the words of the Prophet (blessings and peace of Allah be 
    upon him): “Actions are but by intentions.” This man had intended to pray, 
    and nothing happened to cancel out his intention.

    End quote from al-Sharh al-Mumti‘, 2/296 

    And Allah knows best.