The ornamental design for a toilettrainingincentivedevice, as shown and described.
FIG. 1 is a front view of the toilet training incentive device in a first adjustable position;
FIG. 2 is a rear view thereof;
FIG. 3 is a left side view thereof; and,
FIG. 4 is a front view of the toilet training incentive device in a second adjustable position.
The broken lines in the drawings are for purposes of illustrating portions of the toilet training incentive device that form no part of the claimed design.