Belt Question

I just bought a 2004 660 grizzly from this 82 year old man who used it on his farm. He bought it new and it has what looks like a very easy 1000 miles on it. I had a honda foreman which was shaft driven. I will be using it to plow snow, occasional trail, and dragging a baseball field and don’t want to end up stranded. Since I made the obvious upgrade to the grizzly my question is on average how long do these belts last? 1k, 2k, 5k miles? First post BTW.

Thanks,
Patrick