Do You Have to Do ‘Umrah Immediately Upon Arrival?
Question

I live in Jordan and I intend to go for `Umrah, in sha Allah. I am going to enter ihram from the miqat and go to Makkah.
My question is: when do I have to enter the Haram and perform the rituals of `Umrah? Should I do that straightaway, or can I go to the hotel and take a shower and sleep and rest after travelling, then go to the Haram and perform `Umrah, because it is a long and exhausting journey, and I want to perform the rituals of `Umrah when I have more energy. Please note that I am going to adhere to the conditions of ihram, including not wearing tailored clothing or perfume and so on.
Praise be to Allah.Do you have to do ‘Umrah straight away?
The Sunnah for the one who goes to Makkah for Hajj or `Umrah is to start first of all with al-Masjid al-Haram and do tawaf (circumambulate the Ka‘bah) before he goes to any other place. That is because of the report narrated by al-Bukhari (1642) and Muslim (1235) from `Aishah (may Allah be pleased with her) who said: “The first thing he (blessings and peace of Allah be upon him) did when he came to Makkah was to do wudu then circumambulate the House.” 
Al-Nawawi (may Allah have mercy on him) said: 
“The hadith of ‘Aishah was narrated by al-Bukhari and Muslim. Our companions said: As soon as he enters Makkah, he should not try to find a place to stay or change his garments or do anything else except tawaf. Rather some of the group should stay with their luggage and mounts so that the others can perform tawaf, then they should come back to their mounts and luggage and find accommodation.” (Al-Majmu‘, 8/15) 
Imam al-Shafi` ‘i (may Allah have mercy on him) said: 
“We have not heard that when he entered Makkah he stopped at any place, either in his Hajj or his `Umrah , until he entered the mosque, and he did not do anything when he entered the mosque, either bowing or anything else, until he started with the House and performed tawaf. He did this in both his Hajj and his `Umrah.” (Al-Umm, 2/185 )
From the above it is clear that the Sunnah is for the muhrim (pilgrim in ihram ) to start the rituals from when he reaches the Haram, following the example of the Prophet (blessings and peace of Allah be upon him) – as stated above – and because leaving a long interval may be a cause of committing some of the actions that are forbidden whilst in ihram. 
Can you sleep in ihram?
But if a person is very tired because of having travelled a long way, and he delays `Umrah so that he can rest, there is nothing wrong with that. 
Shaykh Ibn ‘Uthaymin (may Allah have mercy on him) was asked: If a person comes to Makkah and is tired, and he is not able to perform `Umrah until the following day, what is the ruling on that? Is it essential to perform `Umrah as soon as one reaches al-Masjid al-Haram? 
He replied: 
“It is best for the person who has come to do `Umrah to start, before anything else, by doing `Umrah, even before he goes to his accommodation. So he should perform `Umrah because that is the purpose (for which he came). But if he delays it, especially if he is tired, so that he can rest, there is nothing wrong with him doing that and his `Umrah is still valid.” (Majmu‘ Fatawa al-Shaykh, 22/285)
And Allah knows best.