Rat traps will have an instant effect when triggered, whether they kill the rat or trap it. But bait works a little differently. Poisoned bait takes time to work; there will be a delay of days, sometimes even a week or more, before the poison can take effect. While it makes sense to check traps daily, bait is a bit more complicated.
When you first set bait down, you should check on it every few days at least to see whether the rats are taking to it or not. If the rats are, quite literally, taking the bait, you will see evidence in the form of bite marks and missing chunks. How regularly you check on it afterwards will depend on how the rats are reacting to it.
If the rats show little interest and the bait remains largely or entirely untouched, there’s no need to come back and check it every day. Once a week will suffice if the rats aren’t showing much interest. You just need to ensure the bait is still fresh and there are no dead rats in the vicinity.
If rats are taking up the bait rapidly, the first batch should die within the first week. Between taking the bait and dying, rats will largely go about their business as usual. In many cases, they will die in inconvenient and hard to reach places. From the moment you first notice that rats are taking the bait, you should be on the lookout for any signs of dead bodies. If you don’t see the bodies, they will start to decompose after a few days. When that happens, the odour they give off will alert you to their presence.
Once previously popular bait is no longer showing any signs of attracting rats, it could indicate there are no more rats on your property. However, don’t get complacent just because they aren’t taking your bait anymore.