it is no guarantee that he will perform any better than a walk on. In addition, there is no gaurantee that a LS you offer in June will be any better or even any different than a LS you offer in January.
So the real question should be which has more value:
a) a LS scholarship in June vs
b) leaving a scholly open in case a 5 star LB or any other elite athlete has interest in your program and if they don't then still having that scholly available to offer that same LS or a similarly skilled LS.
I would choose option B every time.