First of all, it should be clear that Hajj is obligatory once in a lifetime. If a person has the means to offer Hajj, he should carry it out as soon as possible. One is not advised to delay offering Hajj under any pretext, keeping in mind the fact that Hajj is one of the pillars of Islam. The Prophet (peace and blessings be upon him) said, “Islam is built upon five pillars: testifying that there is no true god except Allah and that Muhammad is the Messenger of Allah, performing Prayer, paying the Zakah, making the pilgrimage to the Sacred House (Hajj), and fasting the month of Ramadan.” (Reported by Al-Bukhari)
Offering Hajj is so easy and simple that you will find no difficulty in offering it. The Prophet (peace and blessings be upon him) showed Muslims the rites of Hajj and ordered his Companions to teach those who were absent. We learn how the Prophet (peace and blessings be upon him offered Hajj) through the authentic Hadiths. Though it’s difficult to explain all rites of Hajj in this counsel – keeping in mind the forms and kinds of offering Hajj – previewing the following URLs will help you a lot in this regard:
Moreover, it should be clear that if a Muslim has performed `umrah before the months of Hajj, then you can perform Hajj when its time comes without being required to offer hadi (sacrificial animal). Also, you have to make your intention to perform Hajj and to assume ihram from wherever you are if you are within (the boundaries of) the miqats. There is no harm in this, because your miqat is the place from where you intend to perform Hajj. This is based on the hadith in which the Prophet (peace and blessings be upon him) said when he designated the miqats: “Whoever is closer (to Makkah) than that, then his place of ihram is from where he began. Even the people of Makkah assume ihram from Makkah.” (Reported by Al-Bukhari and Muslim)
However, in case you performed `Umrah during the months of Hajj, then you have to slaughter Hadi and make the intention to perform Hajj Tamattu` and assume ihram.