It varies - some hitters feel a difference after using it once. For others, it takes a few days. Either way, you will notice a difference in your swing after a week of consistent use.
Does the bat come with anything else?
Yes, along with the Thick Grip Bat, your order includes 8 hitting drills you can use to accelerate the results of your training. You also get 2 exclusive digital bonuses created by Donnie Ecker himself.