Usually they apply within the hour.. and since its a higher limit, it is in effect from that time on.
You should be able to log into the myrogers with your account and see the changes there.
You will need to chat or call in and make sure if this was added immediately (Real Time) or on your bill cycle close date. The bill cycle close date could be a few days or weeks from now. It is best to double check in order to ensure no overage.