Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
As regards your first question, we’d like to make it clear that Ihram has both place and time limits. One does not enter into ihram until one reaches a particular point on the journey to Makkah. The point differs according to the direction from which one is coming. The Prophet (peace and blessings be upon him) defined these points—known as miqats—in the following order:
People coming from Al-Madinah Al-Munawwarah start their ihram at a place called Dhul-Hulaifah. It is better known today as Abyar `Ali, which is barely10 kilometers from Madinah on the way to Makkah.
People coming Syria, Egypt, Palestine and beyond these have Al-Juhfa as their miqat, which is very close to the city of Rabigh.
People coming from Yemen have Yalamlam as their miqat, while those who are coming from the central and the eastern provinces in Saudi Arabia start their ihram at Qarn Al-Manazil near Ta’if. These were the points defined by the Prophet (peace and blessings be upon him).
Later, `Umar added another point because people from Iraq complained that if they were to make their journey through Qarn Al-Manazil, they would add quite a long distance to their journey. `Umar told them to head straight on to Makkah, but they should define a point on their route that is parallel to Qarn Al-Manazil. This spot has come to be known as Dhat-`Irq, which is the miqat of people coming from Iraq and beyond.
Having clarified the above, if there is a controversy regarding the exact place of miqat of prople coming from Nigeria, you can make Ihram from your house or before riding the ship or the plane. You can also visit Madinah first and assume ihram from the miqat of people of Madinah.
Allah Almighty knows best.