Rclone will just skip any items it sees has already been copied, so you can start and stop at any time (it will not resume half-finished files though, those have to be started again).
It will throw a "user rate limit exceeded" or something close to that if you go above the limit.
(@Animosity022 - server side copy does not reference or use the bwlimit)
You can also use these two to manage this if you want:
--bwlimit 8.5M
(limit speed to 8.5MB/sec, or about 68Mbit/sec which is the speed at which you can upload 24/7 and never reach the limit)
--max-transfer 730G
(stop the process once 730GB of data has transfered. Note that rclone does not track if you already used parts of your quota today however, so this only helps to the degree that you know your quota for the day is mostly unused).
But if you run into the limit nothing bad happens... rclone will just continue trying a whole lot and eventually error out on transfering some files. Simply running the same command again when you have more quota to use will transfer any files that errored out because of this.