Make sure to check with the local permitting agency from time to time about the status of your permit. It is your responsibility to make sure your application is still in the system.
There are many jurisdictions where it takes more than four months before they even pick up your submittal to start the review. This gives plenty of time for your application to be misplaced, or damaged in a fire, or any other mishap you might imagine.
A phone call every two to three weeks is a good idea to make sure the permitting agency still has the application in process. Make sure to have the application number, parcel number and address of the project ready when you call.
Good luck and hope your plan reviewer has not left for a three week vacation or is not recovering from an operation before your review was finished.