Why not just view the profile. You can see when the user is registered. As to your account, it's October 24, 2017, 05:32:47 PM. As you can see, this information is public and you don't have an option to hide it nor anyone else unlike the case of your e-mail. No need to go such great lengths.

P.S. You can know when that account is registered thru its UID by the aid of forum's stats but it would not be that accurate to do so.