You mean you're using online services to provide you with trusted timestamp? [1]. But you need to consider how a trusted timestamp merely proves that some photo was definitely taking at or before the attested time. It does not prove that a photo was not actually taken a day earlier and then merely submitted at the attested time. To prove something was not recorded earlier is a little trickier. Need something like a newspaper headline that would not have been available earlier. And then how do you defend against claims that you took the photo early, but photoshopped the newspaper headline at the time it was attested?

[1] https://en.wikipedia.org/wiki/Trusted_timestamping