Praise be to Allah.
If a person wants to do Hajj or ‘Umrah, and he is outside the miqaat boundary, he has to enter ihram from the miqaat. However, if his place of residence is within the miqaat boundary, such as the people of Jedah, then he may enter ihram from his place of residence, because of the report narrated by al-Bukhaari (1524) and Muslim (1181) from Ibn ‘Abbaas (may Allah be pleased with him) who said: The Prophet (blessings and peace of Allah be upon him) defined the miqaat of the people of Madinah as Dhu’l-Hulayfah; that of the people of Shaam (Syria) as al-Juhfah; that of the people of Najd as Qarn al-Manaazil; and that of the people of Yemen as Yalamlam. They are for them and for others who come through them with the intention of performing Hajj and 'Umrah; and whoever is living within these boundaries (can enter ihram) from the place where he starts, and the people of Makkah can enter ihram from Makkah.
The words of the Prophet (blessings and peace of Allah be upon him), “and whoever is living within those boundaries (can enter ihram) from the place he starts” mean: he can enter ihram from the place where he is. As you did not form the intention to do Hajj until after you finished your work, at which time you were in Jeddah, then you may enter ihram from the place where you are, and you do not have to go to the miqaat.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was asked: I was sent (to Makkah) by my company during Hajj season and I travelled with the group as far as Mina, then I decided to ask my work for permission to perform Hajj. Should I go to the miqaat and enter ihram from there, or can I enter ihram from the place where I am?
He replied: You can enter ihram for Hajj from the place where you are, because when you passed the miqaat, you did not know whether you would be given permission or not, so you had not decided to do Hajj. So for example, if they gave you permission in Mina, then enter ihram from Mina; if they gave you permission in ‘Arafah, enter ihram from ‘Arafah.
End quote from Liqa’ al-Baab al-Maftooh, 89/20
He was also asked: In sha Allah, I am intending to do ‘umrah on the day of Hajj, and I am assigned to do some tasks during Hajj season. He said: If my work allows me, and it is most likely that work will not say no. But we say there is a 10% chance that they may say no, as a precaution. He has passed the miqaat now; does he have to go back in order to enter ihram from the miqaat?
He replied: No. If the man has been given some tasks to do and does not know whether he will be given permission or not, he does not have to enter ihram from the miqaat. Then if he is given permission, he may enter ihram from the place in which he was given permission.
End quote from Liqa’ al-Baab al-Maftooh, 178/18.
And Allah knows best.