The chase up into the woods took place 3 minutes after the dispatch was made [9:36] and within seconds of arrival at the school [9:39--9:40].
At the same time [9:40] the LEOs were swarming the front entrance. It's right there in the dispatch. There is news video of this with the 9:40 timestamp.
He shot himself 6 minutes later at 9:46.
Re audio: A transcript is not audio.
There is audio at the link if you prefer that. Transcripts backed by audio with timestamps noted are better.
Interesting interview:
http://www.youtube.com/watch?v=ptbd6qRY358
When this mother arrived at the school the six kids from Soto’s class were running away from the school, there was another mother there, the doors of Lanza’s car were open as if it had been searched, the glass next to the door into the school was broken where it had been shot out, and it was eerily quiet until shots rang out and kids started leaving the building.