Don't wake a sleeping giant...
If your bike is stored for the winter, provided you have taken appropriate storage precautions, you will not do any good and may possibly cause problems by starting it up periodically.
Proper storage includes: remove battery; change oil and filter (ALL the oil.. not just in the crankcase); clean, wash and wax; remove or stabilize fuel.
By starting the bike up periodically all you do is cause partially burned gas and oil to build up in the system. This is the cause of rust and corrosion inside the engine. Likewise, starting a bike in cold weather and running it for a few minutes really puts a strain on the battery, without giving the alternator a chance to recharge it.
When you are ready to ride in the springtime your bike will thank you for letting it sleep undisturbed.