Jonas did not escape according to plan. He had to escape early because he had to take the baby.
Jonas does not see anything wrong with his community until he begins his training as Receiver of Memory with The Giver. That’s when he discovers that his community regularly kills people who don’t follow the rules or don’t measure up to expectations. When he watches his father murder a newborn baby with absolutely no remorse, Jonas knows he cannot stay.
The Giver tells Jonas he never thought there was a way to solve the community’s problems, and make them appreciate why Sameness was a disaster.
"Now for the first time I think there might be a way," The Giver said slowly. "And you brought it to my attention, barely—" He glanced at the clock, "two hours ago." (ch 20, p. 155)
Jonas and The Giver develop a plan. They will prepare Jonas for escape by fortifying him with memories of food, strength and warmth. Then he will sneak out while everyone is distracted by the Ceremony of Twelve.
Things do not go according to plan. When Jonas arrives home, he finds out that Gabe is scheduled to be released. He cannot allow this to happen, so he takes Gabe and his father’s bicycle and leaves the community. He steals leftover food before he leaves.
The original plan did not call for a bicycle or stealing garbage. The Giver had access to vehicles, and food.
The Giver would help Jonas hide in the storage area of the vehicle. He would have with him a bundle of food which The Giver would save from his own meals during the next two weeks. (ch 20, p. 160)
With two people instead of one, it is harder to escape. Jonas also has only the bicycle, and he is on his own. He needs to share his food and his memories with Gabe. He manages to cleverly avoid search planes, and get to the edge of the community.
Lowry, Lois (1993-04-26). The Giver (Newbery Medal Book). Houghton Mifflin Harcourt. Kindle Edition.