Took a look at my drive belt today. I assume it looks good. Looks kind of dirty in there though, no? I have 9800 miles on my bike and I do not know when it was last changed.
It is hard to tell the condition of a CVT belt by visual inspection. If it is cracked or "lugs" are broken off the belt then damage is obvious. But that will not typically be the case. Some measure the width of the belt to check for wear. I simply change mine every 6-8 thousand miles. I've never had one break while on the road and I'd like to keep it that way.
I change mine every 4k. The manual says to check it every 3750 miles. My first one looked pretty bad at 4k so I will change it every 4k from this point on. You can also clean out the inside of the case while you are there.