Mistakes Made in Ihram
Question

We are coming to Jeddah by plane. Is it permissible for us to delay ihram for Hajj until we reach Jeddah? What are the mistakes that people usually make in the state of ihram?
Praise be to Allah.Mistakes made in ihram
Shaykh Muhammad ibn ‘Uthaymin (may Allah have mercy on him) said: 
“Some of the mistakes made by some pilgrims with regard to ihram include the following:
Not entering ihram from the miqat 
Some pilgrims, especially those who come by air, do not enter ihram from the miqat and wait until they arrive in Jeddah, even though they pass over the miqat. The Prophet (peace and blessings of Allah be upon him) defined the miqats and said: “They are for them (their residents) and whoever comes to them who is not of their people.” (Narrated by al-Bukhari, 1524; Muslim, 1181)
Al-Bukhari narrated that when the people of Iraq complained to ‘Umar ibn al-Khattab (may Allah be pleased with him), saying that the miqat that the Messenger of Allah (peace and blessings of Allah be upon him) had defined for the people of Najd was out of their way, or was too far for them, he (may Allah be pleased with him) said: “Look for a place that is in line with it on your route.” (Narrated by al-Bukhari, 1531)
This indicates that coming in line with the miqat is like passing through it. So one who comes in line with the miqat from above, in a plane, is like one who passes through it, so he has to enter ihram when he comes in line with the miqat, and it is not permissible for him to pass the miqat and enter ihram when he lands in Jeddah.
The way to correct this mistake is to do ghusl in one’s house or in the airport, and to change in the plane and put on the ihram garments and take off one’s regular clothes. Then when he comes in line with the miqat he should enter ihram from there, and recite the talbiyah for whatever he intends to do, ‘Umrah or Hajj. 
It is not permissible for him to delay that until he reaches Jeddah. If he does that then he has done wrong and according to the majority of scholars he has to offer a sacrifice which he should slaughter in Makkah and distribute the meat to the poor, because he has omitted one of the obligatory duties. 
Some think that entering ihram wearing shoes is essential 
Some people think that it is essential to enter ihram wearing shoes , and that if a person is not wearing shoes when he enters ihraam, then it is not permissible for him to put them on. 
This is a mistake because it is not essential to wear shoes when entering ihram. Ihram may be done without wearing shoes, and if a person enters ihram without wearing shoes, that does not mean that he cannot put them on afterwards. He can put shoes on afterwards if he wasn’t wearing them when he entered ihram – there is nothing wrong with that.
Thinking that it is essential to enter ihram in the ihram garments and to keep them on until they exit ihram
Some people think that it is essential to enter ihram in the ihram garments and to keep them on until they exit ihram, and that it is not permitted to change these clothes . This is a mistake, because the muhrim (person in ihram) is permitted to change his ihram garments with or without a reason, if he changes them for something that he is permitted to wear during ihram.
In this regard, there is no difference between men and women. Anyone who enters ihram in ihram garments and wants to change it may do so, but sometimes he may have to change it, such as if it becomes contaminated with some impurity (najasah) that he cannot wash without taking it off. And sometimes changing it may be preferable, such as if it becomes very dirty, without there being any najasah, so he should change it for a clean ihram garment.
Sometimes the matter may be one in which he has the choice: if he wants he can change it and if he does not want he does not have to change it. The point is that this notion is incorrect, namely the pilgrim’s belief that if he enters ihram in a certain garment it is not permissible for him to take it off until he has exited his ihram.
Uncovering the right shoulder and throwing the end of the rida over the left shoulder from the time of entering ihram
Some people uncover their right shoulder and throw the end of the rida (upper garment) over their left shoulder from the time they enter ihram, i.e., from the moment they form the intention, so we see many pilgrims – if not most of them – wearing their ihram garments in this manner from the moment they enter ihram until they exit ihram. This is a mistake, because this manner of wearing the ihram is only to be done during Tawaf al-Qudum (the tawaf performed upon arrival in Makkah), not during al-sa’i and not before the tawaf.
Believing that it is obligatory to pray two rak’ahs when entering ihram 
Some of them believe that it is obligatory to pray two rak’ahs when entering ihram . This is also a mistake; it is not obligatory to pray two rak’ahs when entering ihram. Rather the correct view on this matter was that suggested by Abu’l-‘Abbas Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him), who said that there is no specific prayer to be offered when entering ihram, because that was not narrated from the Prophet (peace and blessings of Allah be upon him).
 If a person does ghusl and puts on the ihram garments, then he should enter ihram without praying, unless it is the time of prayer, such as if the time for an obligatory prayer has come or is approaching, and he wants to stay at the miqat until he has prayed. In that case it is better for him to enter ihram after praying. With regard to intending to pray a specific prayer in ihram, the most correct opinion is that there is no specific prayer for entering ihram.