Is It Possible to Determine the Date of Laylat al-Qadr?
Question

Is it possible for anyone to be certain that a particular night is Laylat al-Qadr?
Praise be to Allah.Virtue of doing acts of worship on Laylat al-Qadr 
There are reports which speak of the great virtue of doing acts of worship on Laylat al-Qadr . Our Lord, may He be blessed and exalted, has told us that it is better than a thousand nights, and the Prophet (peace and blessings of Allah be upon him) said that whoever spends this night in prayer out of faith and in the hope of reward will be forgiven his previous sins. 
Allah says (interpretation of the meaning): 
“Verily, We have sent it (this Quran) down in the Night of Al-Qadr (Decree). And what will make you know what the Night of Al-Qadr (Decree) is? The Night of Al-Qadr (Decree) is better than a thousand months (i.e. worshipping Allah in that night is better than worshipping Him a thousand months, i.e. 83 years and 4 months). Therein descend the angels and the Ruh [Jibril (Gabriel)] by Allah’s Permission with all Decrees, (All that night), there is peace (and goodness from Allah to His believing slaves) until the appearance of dawn.” [al-Qadr 97:1-5] 
Abu Hurayrah (may Allah be pleased with him) narrated that the Prophet (peace and blessings of Allah be upon him) said: “Whoever spends this night in prayer out of faith and in the hope of reward will be forgiven his previous sins.” (Narrated by al-Bukhari, 1901; Muslim, 760) 
Out of faith means believing in its virtue and in the reward for that. In the hope of reward means by seeking the pleasure of Allah. 
When is Laylat al-Qadr?
The scholars differed as to the definition of Laylat al-Qadr, and there are many opinions, more than forty as it says in Fath al-Bari. The most likely to be correct is the view that it is one of the odd-numbered nights among the last ten nights of Ramadan. 
`Aishah (may Allah be pleased with her) narrated that the Messenger of Allah (peace and blessings of Allah be upon him) said: “Seek Laylat al-Qadr among the odd numbered nights of the last ten nights of Ramadan.” (Narrated by al-Bukhari, 2017; Muslim, 1169) 
Al-Bukhari included this hadith in a chapter entitled: “Seeking Laylat al-Qadr among the odd numbered nights of the last ten nights (of Ramadan).” 
Why don’t we know which night is Laylat al-Qadr?
The reason why it is hidden is to encourage the Muslim to strive hard in worship and du`a and dhikr during all the last ten nights of Ramadan. This is the same reason why the time when du`a is answered on Friday has not been defined, and why the ninety-names of Allah have not been defined, concerning which the Prophet (peace and blessings of Allah be upon him) said: “Whoever learns them by heart will enter Paradise.” (Narrated by al-Bukhari, 2736; Muslim, 2677) 
Al-Hafiz Ibn Hajar (may Allah have mercy on him) said: 
“The words of Imam al-Bukhari (may Allah have mercy on him) – “Seeking Laylat al-Qadr among the odd numbered nights of the last ten nights (of Ramadan)” – indicate that it is most likely that Laylat al-Qadr cannot be in any month other than Ramadan, and is in the last ten nights thereof, and is one of the odd-numbered nights, but not on any particular night. This is what is indicated by a number of the reports that have been narrated concerning it.” (Fath al-Bari, 4/260) 
And he said: 
“The scholars said: The reason why Laylat al-Qadr has been concealed is so that people will strive to seek it, because if its timing was known, they would limit their efforts to that night only, as we have explained previously about the time on Friday (when du’as are answered).” (Fath al-Bari, 4/266) 
 Is it possible to determine the date of Laylat al-Qadr? 
Based on this, it is not possible for anyone to be certain that a particular night is Laylat al-Qadr , especially since we know that the Prophet (peace and blessings of Allah be upon him) wanted to tell his ummah when it was, then he told them that Allah had taken away that knowledge. 
`Ubadah ibn al-Samit (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings of Allah be upon him) came out with the news of Laylat al-Qadr, but two men among the Muslims started arguing. He said: “I came out to tell you about Laylat al-Qadr, but So and So and So and So started arguing, so (that knowledge) was taken away. Perhaps that will be better for you. So seek it on the (twenty-) seventh and the (twenty-) ninth and the (twenty-) fifth.” (Narrated by al-Bukhari, 49) 
The scholars of the Standing Committee said: 
“With regard to singling out one night of Ramadan as Laylat al-Qadr , this requires evidence to show that it is this night and not any other. But the odd numbered nights of the last ten nights of Ramadan are more likely than others (to be Laylat al-Qadr) and the twenty-seventh night is the most likely night to be Laylat al-Qadr, because of the hadiths to that effect.” (Fatawa al-Lajnah al-Daimah li’l-Buhuth al-‘Ilmiyyah wa’l-Ifta, 10/413) 
Hence the Muslim should not assume that any particular night is Laylat al-Qadr , because that would mean that he is being certain about something concerning which we cannot be certain, and because it means that he is missing out on something that is good for him. It may be the night of the twenty-first, or the twenty-third, or the twenty-ninth. If he spends the night of the twenty-seventh only in prayer, then he will have missed out on a lot of goodness, and he may have missed that blessed night. 
The Muslim should strive his hardest to do acts of obedience and worship throughout Ramadan, and more so in the last ten days . This is the teaching of the Prophet (peace and blessings of Allah be upon him).  
`Aishah (may Allah be pleased with her) said: “When the last ten days of Ramadan began, the Prophet (peace and blessings of Allah be upon him) would tighten his waist-wrapper, spend his nights in prayer, and wake his family.” (Narrated by al-Bukhari, 2024; Muslim, 1174) 
And Allah knows best.