Probably not important at all if he's sending some entirely untrained little kid haha.
I mean, the only part of the map they were missing was a single tiny little chunk that marked the end. If they have the resources and manpower to carve out an entire planet and turn it into a super-duper death(star)planet, they totally could have easily scoured the single star system that the map pointed to and found Luke hella easy. They shouldn't have needed to know the precise planet at that point...