Immediately or Immediately?

Immediately:  without lapse of time; without delay; instantly; at once, 
                       with no object or space intervening


As I read the English Standard Version of Mark 1, I find myself intrigued by the number of times the word "immediately" is used. I counted nine. It's used after the baptism of Jesus, His going into the wilderness, the call of the first disciples, and the acts that follow. The word is causing a distinction in my mind, especially in verses 17-20. For example:  Why did Jesus immediately call James and John, but not Simon and Andrew? Also interesting, Simon and Andrew left their nets immediately while James and John simply left.

And Jesus said to them, “Follow me, and I will make you become fishers of men.” And immediately they left their nets and followed him. And going on a little farther, he saw James the son of Zebedee and John his brother, who were in their boat mending the nets. And immediately he called them, and they left their father Zebedee in the boat with the hired servants and followed him. 
Mark 1: 17-20

Simon and Andrew...Did they leave their nets immediately or immediately?
If they left their nets without lapse of time or delay and at once, then...we are lacking some serious faith. Okay, I am lacking faith. I have the Bible, the full story, at my fingertips all day (technology has left no excuses). Yet when God calls or gives a directive to move from what I know, my obedience is not always immediate. Sometimes I stall spiritually (prayer, followed by fasting, then prayer and fasting with an option to do a full fast if I'm still not clear), which is also known as being paralyzed by fear.

If they left their nets with no object or space intervening, I don't feel as bad. Most times, I need to remove all things out of my way before I can leave my nets...I need to remove my flesh, my fears, and the world. I need to clearly disern the voice I am hearing.
The good news in all of this pondering is we never read Jesus telling James and John, "Get to the back of the line because when I called you, you failed to leave immediately."
Now that helps a fisher-lady like me!