The Holy Prophet enjoined Fitra charity on Muslims a saa of dates or a saa of barley upon every slave and free man, male and female, young and old, and ordered that it should be paid before the people go out for performing ( Eid-u-Fitar )prayer. ( Bukhari )
Fitrana is compulsory on all Muslims regardless of their status or age. The very poor Muslims those who don’t even have approximately 2kg of essential food are exempted from paying Fitrana.
An old man who was not able to perform fasting in Ramadan due to serious illness or old age is not exempted from paying Fitrana.
The head of the family can also pay Fitrana for his kids, servants and dependents.
The time is limited in this charity Fitrana becomes obligatory from sunset on the last day of Ramadan and remains obligatory until the Eid prayer. It can be paid a couple of days before Eid as many companions of The Holy Prophet used to give Fitrana in Ramadan.
Hazrat ibn Umar would give those people who would accept it and he used to pay it one or two days before the day of Eid-ul-Fitar. ( Bukhari )