When is Laylat al-Qadr, bearing in mind the اختلاف in the start of Ramadan's fasting among Islamic countries?

Allah Almighty concealed Laylat al-Qadr for a great wisdom, which is to encourage believers to strive in worship throughout the nights of Ramadan (definition). There is no way to know it in advance. A Muslim should seek it in the last ten nights, with the odd-numbered nights being more likely, and the night of the twenty-seventh being the most hoped for. Whoever wishes to go to great lengths in seeking it should take the first sighting into consideration.