Those chunks make little difference.
The grow medium will retain a lot of previous fertilizer, and new fertilizer added won't be the sole determinant of nutrients in the medium.
Add more chunks now, fewer chunks later, and the grow medium will be fine.
The important thing is to make sure the container has the chunks evenly mixed so that, on average, we'll get the right amount of them.
I keep about 2 cups in an airtight container, the dose by sitting it on a scale, quickly opening the container, and scooping out the right amount of MC.
And I never worry about chunks.