Since old ages, people have marked some special days in a year to rejoice and celebrate and to be happy. In islam, the two official days to rejoice are the two eids. But these special occasions are for every muslim not only for those who can celebrate and feel happy. This is why is has been made obligatory for the muslims who are sahb-e nisab to pay fitrana to the poor before eid prayer.
The best is to pay them some days before eid so that they can also spend the money or keep it to be spent on the day of eid.
Fitranah is different from zakat in a manner of its measuring and its distribution. It is calculated as 2.50 wheat per head in the family. Suppose if there are 7 people in your home, the 2.5 kg wheat per head will become 2.5*7= 17.5 kg. Thus the family will pay the money equivalent to the 17.5 kg raw wheat to the poor.
This is not a huge amount which cannot be paid so it should be paid some days before eid. Many people still pay the standard money against 2.5 kg, but the better way is to pay 2.5 kg equivalent current amount of wheat.
If wheat prices go up, it will make the fitrana money a little more which might not harm the sahib-e nisab much but can do good to the poor family. In this way, the poor will get more and will be able to spend his eid day in a better way.
Islam has made it obligatory for the muslims to remember their other muslim brothers and sisters in the time of happiness and in the times of sorrow. If it was not made obligatory, people would have never thought about poor and the world would be a worst place for those who do not have much to earn.
ALLAH is the sustainer of all, and HE has made ways for his people to spend money and to get money. Do not forget to pay fitrah and do not be hesitant to pay money in the way of ALLAH because when you spend for ALLAH , HE remembers it.