That's a good question. I don't pretend to understand everything in the book of Revelations or Isaiah, for example. There is considerable disagreement between Jews and Christians on the prophet Isaiah, which is well beyond the subject of this thread, and greater thinkers than I have tackled them. But you're right. No there is no fixed time within biblical prophetic works. Those prophecies generally refer to the time when the kingdom of the Lord is at hand. No one knows when that time will come. Some people, of course, believe it is real soon now. No one, though, can say with exact certainty as to when.
However, Hinn does give time frames. He predicts recent events, but somehow none of his followers seem to remember his false predictions and always excuse his false teachings. Some time during the 1990s, for example, Hinn predicted Castro would die and there'd be a Christian revival in Cuba. Another said that by the year 2000 all homosexuals would be punished by the Lord with death. Not in the way one might think, either: but to be consumed by fire. Not long after September 11th he predicted that some time between 2002 and 2004 Oral Roberts and Jimmy Swaggart were to both pass away in close succession, and after that there was supposed to have been a terrorist attack on this country that would make 911 look like peanuts. This is one of the predictions that I saw him make personally at one of his events I attended. He clearly indicates that the Lord is speaking through him, that these events are ordained to come about.
I guess Hinn is not a good enough con man to refrain from giving time frames, although if he is a lurker here, we just helped him with that. As an agnostic, I could care less what sort of religious doctrine Hinn and his televangelist ilk promulgate, but I think that people give money to televangelists for the same reason I chose to spend my money on professional wrestling: it's all entertainment. I look at Benny Hinn the same way I look at any musician, actor, or sports star. Some people just like their act.