Passage
and immediately, having left their nets, they followed him.
and immediately, having left their nets, they followed him.
Mark 1:16 And, walking by the sea of Galilee, he saw Simon, and Andrew his brother, casting a drag into the sea, for they were fishers,
Mark 1:17 and Jesus said to them, `Come ye after me, and I shall make you to become fishers of men;'
Mark 1:18 and immediately, having left their nets, they followed him.
Mark 1:19 And having gone on thence a little, he saw James of Zebedee, and John his brother, and they were in the boat refitting the nets,
Mark 1:20 and immediately he called them, and, having left their father Zebedee in the boat with the hired servants, they went away after him.
The verse centers on "immediately", "having", "left", "nets", and "followed". It is saying that the verse draws attention to "immediately" and "having", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 17's "and Jesus said to them Come ye..." into verse 19's "And having gone on thence a little...", so "immediately" and "having" belong inside that flow. In Mark context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "immediately" and "having" with trust shaped by these words, not by a vague optimism outside the passage.