before starting Herbology, or until ending

Then, one breakfast time, Hedwig brought Harry another note from Hagrid. He had written only two words: It's hatching.
Ron wanted to skip Herbology and go straight down to the hut. Hermione wouldn't hear of it.
"Hermione, how many times in our lives are we going to see a dragon hatching?"
"We've got lessons, we'll get into trouble, and that's nothing to what Hagrid's going to be in when someone finds out what he's doing --"
"Shut up!" Harry whispered.
Malfoy was only a few feet away and he had stopped dead to listen. How much had he heard? Harry didn't like the look on Malfoy's face at all.
Ron and Hermione argued all the way to Herbology and in the end, Hermione agreed to run down to Hagrid's with the other two during morning break. When the bell sounded from the castle at the end of their lesson, the three of them dropped their trowels at once and hurried through the grounds to the edge of the forest. Hagrid greeted them, looking flushed and excited.

***
Did Ron and Hermione argue before starting Herbology, or until ending of the Herbology?