There was a pretty whelming show called Travelers that had a similar premise of restrictions on time travel, but instead of imprecise its the opposite, it has to be so precise that it's very limiting because you can't send matter back in time, only information so they take over host bodies at very specific locations and moments. If they have the coordinates or the time incorrect, it misfires and the mind of the traveler just is lost.

Due to butterfly effect shit changing the future, there's tons of rules like you can't travel back further than any previous trip. They started as early as they could once cell phones were invented and they had coordinates, and then only sent back new travelers after that point in time. Basically there's future day 0 when they first tested time travel, and past day 0 when the first time traveler arrived. Those two times are synched up, and the future travelers have to come back at the same time (future day 252 and past day 252, etc).

In a post-apocalyptic future, thousands of special operatives are tasked with preventing the collapse of society. These operatives, known as "travelers", have their consciousnesses sent back in time and transferred into the "host" body of present-day individuals who are about to die, minimizing unexpected impact on the future. The transfer requires the exact location of the target, made possible by 21st-century smartphones and GPS, providing time, elevation, latitude, and longitude (TELL) coordinates that are archived for use in the future. No transfer can be safely made to a time prior to one already performed.