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.
In this fatwa:
2- However, it can be paid earlier than that to enable the poor to provide their needs for the `Eid day, as the main aim of it is provide the poor with their needs and make them happy on that blessed day.
Answering your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
You probably mean Zakah of al Fitr not Zakah of wealth.
First, many people like to make Ramadan as the time of paying Zakat al-Mal and they adjust their Zakah year to do that. This is because all acts of benevolence are more rewarded in Ramadan than in other times.
Zakat al-Fitr is due in the last few days of Ramadan and must be before the morning of the `Eid day. The intention of it is to bring happiness to the poor on the day of `Eid.
It is permissible to pay it earlier than the last few days of Ramadan if this is necessary to make it reach the poor just for the `Eid.
In other words, this is a seasonal payment that has a special time-related objective. It must stick to this time frame. And to do that we may, and sometimes MUST, pay it a little in advance as much as this is necessary to make it on time to the poor.
This is especially the case when we pay it through intermediaries like Muslim charities which carry it to other countries/places.
Allah Almighty knows best.