I'm with Mikey. Power braking your CVT is a good way to bring your drive belt to an early death and possible damage to your pulleys. You should be able to move from a stop without spinning the rear tire.
Of course, you need to go easy on a new belt for about 50 miles. Stop and go riding is not 'Going Easy'. A quiet road where you can just cruise and not have to engage and disengage the belt is best. Vary your speeds some to let the pulleys move the belt around if you can.
No hard acceleration, which power braking from a stop would be just that.
One of the best things you can do for belt longevity is to replace the OEM paper air filter on the right side with a K&N CM-9910 air filter. It will flow more air, resist clogging (which is important because the CVT filter handles a lot of air flow). Belt temperature is critical and this mod improves CVT cooling quite a bit.
When changing the belt, don't scrimp on cheaper products. These belts come in a variety of qualities from aftermarket suppliers. If you go this route, get the best belt they make (Gates, for example). We had a customer put a cheap belt on their Ryker thinking a belt is a belt. It blew up in short order doing a fair amount of damage to surrounding components which increased the repair cost.
Treated right, the belt will go beyond the recommended 10,000 mile service interval. But don't try to run it too long. A failed belt will usually take other components with it. Not to mention, it will leave you stranded.
We've also had OEM belts fail at much less than the recommended mileage (4,000 miles for example). We found the OEM paper filter completely clogged on this Ryker, which lead to the early demise. In any case, it is a good idea to check the right side air filter as a routine measure. Especially if you are running the OEM paper item.