If you tell me something along the lines of “Next month we are going to announce a product that will change everything!” what have you told me? You’ve told me that you feel the need to manufacture hype. That tells me that you don’t believe the product will be successful on its merits.
Ideally, you shouldn’t announce a product until it is ready to be bought. Perhaps nothing dampens enthusiasm as much as the waiting. There are times, though, when it makes sense to announce a product earlier.
When you do announce a product, though, you should be able to show it doing exactly what you say it will do. If your product isn’t good enough that showing it sells it, then you may need to go back to the drawing board rather than trying to build hype.
The big caveat is the trap of demoïng well. While a good demo is the best way to sell your product, you need to make sure it is as good or even better with long term use.