Grace period to use newly added coverage?

It depends. Some companies will not pay a claim until the policy has been in effect for 30 days. Also, they may cover it but then cancel the policy. You would need to be able to provide proof of the date of the incident since it was within a day of adding the coverage. Here is information on what to expect when you file a claim. One more thing to keep in mind, hitting a deer would be covered under your comprehensive coverage. This time of claim can impact your rate for up to three years. Good luck and if you have any questions don't hesitate to ask.