There's really no way to send a message like that. But, time seems to freeze while you're here. People have reported returning to the exact moment that they were taken from, people are pulled from the same exact moment from there worlds into this world months apart, and people from the future show up too. So the likely theory is that time freezes until we get back home or that multiple timelines of every world exist. I lean towards the former.

Regardless, your parents won't notice you're gone, so, that's one less thing to worry about.