All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The scholars differed in opinion about when the incident of Al-Israa’ and Mi'raaj (the night journey of the Prophet to Jerusalem and ascension to the heavens) happened; some said that it happened one year before Hijrah (migration to Madeenah) and some said that it happened five years before Hijrah.
The scholars also differed in opinion about the month when the Mi’raaj took place; some said that it took place in Rabee’ Al-Awwal, some said that it took place in Rajab and some said that it took place in Ramadan, or Shawwaal, etc...
However, the most correct opinion is that there is no authentic evidence which proves exactly when the Mi’raaj took place, as per the view of prominent scholars, like Ibn Taymiyyah and others .
Allaah Knows best.