The answer to 'when to treat for rodent' is that you should treat for rodents as soon as you notice signs of their presence, such as droppings, gnaw marks, or noises in the walls or attic. Rodents can breed quickly and cause significant damage to your home, so it's important to address the problem right away.
The best time to treat for rodents is in the fall and winter, when they are more likely to seek shelter indoors. However, you should be vigilant for signs of rodents year-round and take action as soon as you notice them. Proper rodent control involves a combination of exclusion (sealing up entry points), removal (trapping or baiting), and prevention (eliminating food sources and nesting areas).