Home fires can happen at any time, but they generally increase during the fall and winter, with December and January being the peak months. Home fires are also more common on Saturday and Sunday, and tend to peak between 6:00 and 7:00 PM. (American Red Cross)
So it is suggested that you check your fire alarms monthly during the cooler months. In older alarms you may need to change the batteries, but in newer alarms the batteries are sealed. Most of these are made to last for up to 10 years, but never trust that.
If you are unsure how to test them, or unable to test or do maintenance on them, it is possible that your local fire department may be of assistance. You can find out by calling the non-emergency number for the fire department and asking.