Why do you think Jonas put off/ throw away his pill (for the stirrings)?
I think that it could be possible that Jonas wants to have dreams (sexual dreams) and he wants to tie his dreams and that what he feels with the memories he got from the giver. He wants to feel different feelings and he maybe wants to discover new things that other people didn’t feel/discover till now, for example the colors. Jonas wants to see the color of the skin of the humans he dreams about and he will get another (sexual) feeling.
The other possibility is that Jonas wants to have a change (which is in my opinion more probable than the first possibility) in the community. It is a rule to take this pill and now Jonas puts them off. So he broke a rule and I think that he now tries to change other things, too (for example the rules in the community). This was the first step of Jonas for trying to change some things in this community.