I don't know that there's any definitive answer. It depends on the tire, how tight you get the tension on the roller (you want it tight enough that it doesn't slip at all), and how much wear the tire already has. Plus, I don't know that a trainer necessarily eats everyone's tires. Yes, they get some wear to them, but that happens on the road, too.

Still, if it were me I'd find a cheaper tire and use it indoors and out for the rest of the fall and winter. I'm not why it's important to wait if you're otherwise worried about ruining your good tire.