We went over this not too long ago in another thread. Dylan and Eric came to the school twice. Once to set the bombs, they left and went over to Clemente Park to "gear up" and then came back. When Eric pulled in the 2nd time is when Brooks saw him.
Here's the timeline I posted in the other thread.
10:59 - Eric drops bomb off
11:00 - Dylan drops bomb off
11:00 - 11:10 - They drive to Clemente Park to gear up and put their trench coats on
11:10 - 4th period finishes and Brooks makes his way outside
11:12 (give or take a few minutes) - Eric pulls into the parking lot and Brooks sees him
11:12 - 11:15 (give or take a few minutes) - Brooks confronts Eric about missing class, Eric tells him to go home.
11:17 - Bombs fail to detonate
11:19 - The boys start shooting
And here is the link to that thread.[You must be registered and logged in to see this link.]
"I love everything you do, when you call me fucking dumb for the stupid shit I do"