Praise be to Allah.
Hajj tamattu‘ means entering ihram for ‘umrah only during the months of Hajj – the months of Hajj are Shawwaal, Dhu’l-Qa‘dah and Dhu’l-Hijjah – so when entering ihram for it, one should say: “Labbayk ‘umratan (Here I am for ‘umrah).”
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said, describing ‘umrah of tammatu‘:
When the pilgrim reaches the miqaat, she should do ghusl as in the case of janaabah, and apply the best perfume he can find to his head and beard, then put on the ihram garments, an izaar (lower garment) and rida’ (upper garment). It is preferable for them to be white and clean. Then he should say: “Labbayk ‘umratan (Here I am for ‘umrah).” There is no need for him to say that he is connecting it to Hajj, exiting ihram in between, because he has already formed the intention in his heart that he is going to perform Hajj. So he should say: “Labbayk ‘umratan, Labbayka Allaahumma labbayk, labbayka laa shareeka laka labbayk. Inna al-hamd wa’l-ni’mata laka wa’l-mulk, laa shareeka lak (Here I am for ‘umrah. Here I am, O Allaah, here I am. Here I am, You have no partner, here I am. Verily all praise and blessings are Yours, and all sovereignty, You have no partner).” Men should raise their voices when saying this, and it should be understood that no tree, rock or brick hears him but it will testify on the Day of Resurrection that he said this Talbiyah. What the Talbiyah means is responding to Allah, may He be glorified and exalted, because the word “labbayk” means: I am responding to You. He should continue reciting the Talbiyah until he begins the tawaaf of ‘umrah. When he reaches Makkah, he should do tawaaf and sa‘i for ‘umrah, shave or cut his hair, and exit his ihram. Then on the day of at-tarwiyah, which is the eighth day of Dhu’l-Hijjah, he should enter ihram for Hajj only and do all the actions of Hajj. So the one who does tamattu‘ does a complete ‘umrah and a complete Hajj.
End quote from al-Liqa’ ash-Shahri.
The one who is doing Hajj tamattu‘ enters ihram on the eighth day of Dhu’l-Hijjah from the place where he is staying. When he enters ihram for Hajj, he does the same as he did when he entered ihram for ‘umrah, doing ghusl and putting on perfume. So he should form the intention to enter ihram for Hajj and say “Labbayka Hajjan (here I am for Hajj)”, then recite the well-known Talbiyah.
The scholars of the Standing Committee for Issuing Fatwas said:
With regard to the one who enters ihram for ‘umrah from the miqaat, intending to follow it with Hajj tamattu‘, when he has done ‘umrah he should exit ihram. There is nothing wrong with him going to Jeddah or elsewhere, then entering ihram for Hajj from the place where he is staying after doing ‘umrah.
End quote from Fataawa al-Lajnah ad-Daa’imah, vol. 2 (10/76-77)
Shaykh Ibn Baaz (may Allah have mercy on him) said:
What is prescribed for the pilgrim who is not in ihram is to enter ihram on the day of at-Tarwiyah from the place where he is, whether he is inside Makkah or outside, or in Mina, because the Prophet (blessings and peace of Allah be upon him) instructed those who had exited ihram after ‘umrah to enter ihram for Hajj on the day of at-Tarwiyah from the places where they were staying.
End quote from Majmoo‘ Fataawa Ibn Baaz (16/140)
As you are going to do ‘umrah on the seventh day (of Dhu’l-Hijjah), you should cut your hair after finishing ‘umrah, and not shave your head, so that some of your hair will remain for you to shave it off during Hajj. The Prophet (blessings and peace of Allah be upon him) instructed his companions, during the Farewell Pilgrimage, to cut their hair following ‘umrah, because their arrival was on the morning of the fourth day of Dhu’l-Hijjah. This indicates that cutting the hair in this situation is preferable to shaving, and it is better so that the head can be shaved during Hajj. For more information please see fatwa no. 31822
The actions on the Day of Sacrifice, for the pilgrim who is doing tamattu‘ are, in order: stoning Jamrat al-‘Aqabah, offering the sacrifice, shaving the head or cutting the hair, tawaaf al-ifaadah and sa‘i. This is the best way, because this is what the Messenger (blessings and peace of Allah be upon him) did. For more information, please see the answer to question no. 106594
If the pilgrim does some of them earlier and others later, or he does some of them after the Day of Sacrifice, there is nothing wrong with that.
The scholars are unanimously agreed that it is permissible to delay shaving the head until the last of the days of at-tashreeq, but if the pilgrim delays it any longer than that, then he must offer a compensatory sacrifice, according to some scholars. See al-Mawsoo‘ah al-Fiqhiyyah (10/12-13)
Try to do your Hajj with one of the scholars or seekers of knowledge, so that you can ask him whatever you need to know about Hajj and ‘umrah.
And Allah knows best.