Depends on the exact injury. If it's a clean tear without meniscus or MCL damage, then 6 months is the normal time table for a torn ACL.
If the meniscus, cartilage or MCL were injured too (which can happen when tearing your ACL) we're looking at 8-12 months.
Let's hope it's 'just' a torn ACL with no colleteral damage, which is bad enough, especially for a young and athletic guard like Shump.
With a close to perfect rehabilitation, good nutrition and a well-executed surgery he should be able to regain his pre-injury shape, but that will take time. You can add another 2-3 months to the 6-8 until he's in full game shape again.
I just hope everything goes well for him. Great young player who deserves a career.
I know this is unfair, but I wish this would have happened to Lebron's flopping ass.