Why did it take 23 years for the Quran to be revealed? It started in Ramadan and according to some narrations it may have ended in Ramadan.

After it started in Ramadan, it came down to Prophet Muhammad (PBUH) as and when it was needed. Every year Jibril (AS) would come and consolidate all that had been revealed.

In the last year of revelation, Jibril (AS) came down and revised everything twice with Prophet Muhammad (PBUH).

The Quran was revealed to the heart of Prophet Muhammad (PBUH) so that he would be one of the warners.