It depends on what is your product marketing strategy (sorry for connecting three buzzwords, but if you are investing hundreds of thousands of [currency] your should have one unless you’re very rich or lucky).
One reason to announce things early is to be faster than the leaks, a factor to consider especially for innovative products and/or popular brands. You keep control of your marketing and you get a first wave of feedback that helps you fine tune next steps. If you are onto something, will start creating an expectation and some of you potential customers will start saving or waiting to buy similar products. If there is questions, criticism, bad press… you are ready to respond.
If you product is leaked (and it’s a real leak), then most likely than not you will start the public life of your leaked product with the wrong foot, and it will take a lot more work to regain control over your own story.
I don’t know whether this is a thing for music instruments, but in other industries you may need to file trademarks and patents, and apply for certifications, and the related public organizations you need to work with have public records. This is another reason to announce before someone posts a link to a boring document that makes people speculate, sometimes in very surreal ways.