The Grammar of Time Travel

[AJS-]

Would you need to create a new tense for time travel?

Obviously in an idle moment, I was thinking about how to explain to someone in the past that I built a time machine in the future, and it would be incorrect to use the past tense for something that happens in the future. For example "I built a time machine in ten years time."

It's also wrong though, to use the future tense for something that has clearly happened, hence enabled this situation "I will build a time machine that will get me back here" because it's happened already, and you'll just sound like a lunatic. Rather than the sane and reasonable time travelling grammaticist that I am.

You could mix the tenses saying something like "I build the time machine in 8 years time, then travel back to now, which explains my presence at this time." But it seems a bit messy.

Is there a past-future tense already or did I just invent it? And what form should it take?

[AJS-]

But you will be on the M1 for two hours today if you go back to this morning and then started having travelled the same way again for the first time. See what I mean?

[AJS-]

Wenting. That's the sort of think I did looking to found.