Simple answer. Assign the ownership of the patent prior to closing any investment that is sufficient to market validate your invention. Investors will require an absolute assignment of ownership of any intellectual property. Given that you don't actually have a patent yet, you will be doing a general assignment that will include all assets and rights around the idea.

I would also caution you not to over-emphasize the value of a provisional patent or patent application in-process. There is *zero* value to a provisional patent or patent in-process so don't let this distract you from operating your business and building out your product/service.