Either you or the insurance company agrees to cancel the contract from the inception - as if it never existed.

How would a contract become voidable? If you deliberately misled the insurance company then the company could say the contract was null and void. If you chose to cancel the policy before it was issued and your agent or broker was able to negotiate a void then you would not be charged time on risk.

If your situation was such that the insurance company chose not to issue the policy because you did not meet their underwriting guidelines then the company would have two choices. One is to grant temporary coverage for a limited period of time to allow you to get alternate insurance. The other is to void the policy and the coverage is not and was not ever in force.

This is a good reason to always be open and communicate your situation fully.