There's definitely been an issue for me in the past with what MxHero regards is my current time versus the scheduled time. normally have to work the slider as though its something that needs training. Also to help myself, I always make a test message for 5 mins from now and if it doesn't go then there's clearly an issue and I reconsider scheduling using mxHero. Not a solution but doesn't create me an additional problem, at least that. It is tedious to do this but my mails are important enough.

If Bcc plugins worked properly in Chrome (or indeed through the mxtoolbox) this could be solved but all of them are flawed in one way or another. e.g. hard coded to default for every email blindly duplicating, or only support one address at a time, or need to be cleared manually when not needed. None of which are better scenarios than adding a Bcc manually to get a capture of the sent email.