Excuse 1: “I will wear it when Allah guides me”

Are you serious? Hasn’t He already guided you by sending His Noble Qur’an and making you a Muslim?

Excuse 2: “I am still young I will wear when I get older”
How can you guarantee your own life until tomorrow? 
The Angel of Death can visit you at any moment to take your life. Death doesn’t discriminate between the young or the old. We should all race to obedience to answer the call of Allah:”

سَابِقُوا إِلَى مَغْفِرَةٍ مِّن رَّبِّكُمْ وَجَنَّةٍ عَرْضُهَا كَعَرْضِ السَّمَاء وَالْأَرْضِ

Race with one another in hastening towards forgiveness from your Lord and Paradise the width whereof is as the width of the heavens and the earth. [Sura Al-Hadeed 57:21]

Excuse 3: “It is too hot to wear a hijab”
Allah gives an example by saying: 

نَارُ جَهَنَّمَ أَشَدُّ حَرّاً لَّوْ كَانُوا يَفْقَهُونَ

Say: “The Fire of Hell is more intense in the heat if they only understand.”
[Sura At-Taubah 9:81]

Understand that Shaytan has trapped you and he is dragging you from the heat of this world to the heat of the Hellfire. Free yourself from his net and view the heat of the sun as a favor and not an affliction especially if it reminds you of the intensity of the punishment of Allah which is many times greater than the heat you feel now.

Excuse 4: “I ‘m afraid that if I wear the hijab I will take it off later because others did it”

If everyone was to apply that logic then they would have left the Deen in its entirety! They would have left off salat because some would be afraid of leaving it later. They would have left fasting in Ramadan because so many are afraid of not doing it later but If you hold tight to the causes of guidance and taste the sweetness of faith you will not neglect the orders of Allah after having held to them.

May Almighty Allah make it easy for you.