Christian tells Jack to count to five, Jacob gives Jack his Apollo Bar

In sometime around 2001, Jack is performing his first major solo surgery and cuts the patient's dural sac. Jack starts to panic and Christian Shephard steps forward and says "Look at me." He then says "Count to five" and Jack angrily says "What are you talking about." Christian says that he needs to stitch up the girl so she isn't paralyzed for the rest of her life. He continues saying "The only way you're gonna do that is not to be afraid. So close your eyes, count to five, and then fix her, Jack. Or I'll have to fix her for you." Jack closes his eyes, counts to five and then asks for the sutures and finishes the surgery.

After the surgery, Jack attempts to buy an Apollo Bar from a vending machine and it gets stuck. He slams his palms into the machine and then walks away.

Christian walks towards him and tells him that girl is going to be okay and is responsive to stimulis below the waist. Jack tells Christian that he embarassed him in front of his entire team by putting him in a time-out during his first major procedure. He continues saying "Dad, I know you don't believe in me, but I need them to." Christian says "Are you sure I'm the one who doesn't believe in you, Jack?" and then walks away.

At that moment, Jacob pokes his head around the corner and asks if one of the two Apollo Bars he's holding is Jack's. Jacob's finger touches Jack slightly has he hands him the candy. Jack shows a slight smile and then walks away.

The surgery scene is the one that Jack told Kate in the pilot when she is stitching up his wound in the pilot. He later made her recount the story when she and Sawyer escaped from the Hydra island in season 3.

Also, Jack is the last of the 815 survivors that we see Jacob touch prior to the crash.