Technically, a person becomes a saint when he/she dies and goes to heaven. For Saint Theresa, this would have been September 30, 1897. She was officially recognized a saint by the Church (canonized) May 17, 1925.
Therese of Lisieux has been recognized as a saint since her canonization date of May 17, 1925.
The actual date of when Valentine of Rome died and became a saint are unknown. We do not know his age.
The feast day of a saint can be any random date or it may fall on the commemoration day of some event of the saint's life, such as their date of death, the day of their canonization or other such event.
Francis of Assisi became a saint July 17, 1228. This was just short of two years after he died.
He wasn't acclaimed a saint until he was dead, in the Catholic Church having the title "saint" means that you have died and gone to heaven. Patrick was about 74 years old when he died and entered heaven. Sources vary on his date of birth and date of death.
Saint John was one of the twelve apostles of Jesus, and known to be the one most beloved by Christ. The apostles weren't canonized, but became saints, nonetheless. Therefore, there is no known date of when he became a saint.
Please complete your question. The date for what of Saint Apollonian?
St. Sebastian was declared a saint by popular acclaim long before a formal procedure was in place for canonization. There is no specific date when this happened. However, as he died a martyr, he became a saint the moment he died about the year AD288.
Saint Adele has an unknown Birth and Death
Often, the date the person died, if known, is considered the feast day of when they entered Heaven, or became a saint. However, this is not a firm rule and any date could be selected.
His date of birth is not known. There isn't a date on which he became a saint, as many old saints were not officially canonised, but made saints by popular acclaim, unlike modern saints. So, as it is believed that he died on the 17th of March, that day is used for Saint Patrick's Day.
There is no Saint Kein. However, if you mean Saint Kevin, Saint Kevin of Glendalough was born about the year 498. The exact date is not known.