Vicky,
Sorry to hear you joined our ankle club.
Range of motion (ROM) exercises are very important to prime your healing but busted ankle for demands of weight-bearing and walking later.
I suffered a medial bimalleolar fracture with sprain, and of course I started these exercises as soon as my attending doctor allowed it. If x-rays show your fracture is mending well enough these gentle ROM movements are not going to hurt you.
As far as how much ROM exercises to do, I would say it all depends. It depends primarily on any collateral soft tissue (that is, connective tissue intimately involved with and all around ankle joint: ligaments, tendons, muscles, nerves, fascia, joint capsules) damage you sustained (along with the fractures) in your accident.
When you are non-weight-bearing in a CAM boot or cast these soft tissue issues, if they exist, usually are not readily apparent. They will make their presence loudly known when you add the stress of weight and movement later.
I would suggest doing limited reps of ROM routines, and then slowly work up the rep counts until you feel too much discomfort or pain, then back off. You don't want to put ankle in too much distress too soon. But if it feels good and there is little or no pain then simply do more.
Icing may help with any discomfort and swelling. Remember that an injured ankle is still in an inflammatory state as healing processes are underway.
The more exercise you do now, and later when you are in weight-bearing status, will pay off in spades with a speedier and more complete recovery.
It is vitally important to implement appropriate and extensive ankle rehab exercises for as long as it takes to rebuild strength and stability in ankle joint. Failure to get joints and supporting soft tissue like ligaments back to normal function could spell trouble later in form of degenerated cartilage/joints (the end state which could be chronic ankle dysfunction and arthritis). You can see this eventual progression play out in so many sad stories on this forum.
In your rehab program, don't forget knee and hip exercises-- they are important in getting back your normal walking gait after being out of action for so long.
Also, balance and proprioception exercises are just as important in getting ankle biomechanics back to normal.
Best of luck to you. 