While grammatically correct, it's unusual to start a sentence with "hitherto". It sounds very old-fashioned and might make your writing seem stilted.
Here are some examples:
* Awkward: Hitherto, the company had never released a product like this.
* Better: The company had never released a product like this before.
If you're trying to create a specific tone or evoke a historical setting, you might use "hitherto" at the beginning of a sentence, but generally, it's best to find a more modern way to express the same idea.
