oddly rats are nervous about new things near their homes. When I first used bait boxes to rid us of a rat population explosion it took nearly a week before they started taking it then it was gone in a day. Replenished and gone in two days, refilled and that lasted quite some time as the rat population was wiped out. To rid the population I used the chunx with bromine to be brought back to nests and feed to the young. Once that bucket was empty I use poison to kill the rodents before they take up home. Bait boxes are rather inexpensive. I keep one right in the run and one in the shed where feed is kept at nights.
https://www.tractorsupply.com/tsc/product/tomcat-rat-bait-station
Idea of what bait station is. Mine have key. The one above you can secure lid with your own wire twist or zip tie. Zip tie you've have to cut every time you check it, I'd use a short length of wire and twist it like a bread bag tie.