When does the young man who gives zakat begin calculating the zakat on his money after repenting from abandoning prayer: is it from the date of his repentance, or from the date he reached the nisab while not praying?

Scholars have held that if someone abandons prayer out of denial of its obligation, they are a disbeliever by scholarly consensus. However, if they abandon it out of laziness, there is a difference of opinion regarding their disbelief, and the chosen view is that they are a disbeliever. If a Muslim possesses the nisab and a year passes over it, then they apostatize after the year has passed, the zakat for that year is not waived from them, because the apostasy occurred after the zakat became obligatory upon them. But if they apostatize before the year is complete, the year is interrupted by that, and if they return to Islam, they begin a new year from the time of their repentance. If a Muslim abandons prayer and was following scholars who said that the one who abandons prayer is not a disbeliever, or if that was the prevalent opinion among the people of their country, then they are not ruled to be a disbeliever, and the rulings of Islam remain applicable to them, and the obligation of zakat continues upon them. If a Muslim forgets the month in which their wealth reached the nisab, they should investigate and act upon what they most likely believe to be true, and take the more cautious and more absolving approach for their conscience.