I usually lay one in the afternoon and then track it the next morning. The amount of time that you want to age it depends on the individual dog…..how far are they in their training and how much nose do they have? You’re wanting to present them with whatever challenges them.... so adjust according to how your dog responds. If she does well on a 12 hr track then try 15 hrs…then 18 hrs…..until eventually you work up to 24 hrs.