Don't bother finding maxes. I would not suggest that. Your precious time will be wasted once you've injured yourself. You don't want 'maximum intensity' (for this routine that is somewhat of an idiom, you won't be generating maximum intensity from anything that is 5x5)
The best plan of attack for this kind of routine is patience lol. Start off slow with a light and manageable weight and add small increments. The whole key to rippetoe's program is the linear progression. You don't want to be struggling at week 2, which means you need to stop and think whether your muscles or your ego is loading the bar (so to speak). DO NOT use an aggressive style of progression on this. Keep the weights lower and work through the program properly and you'll see results.
EDIT: I wrote this up before Eric came, so I didn't see his post. (When I said quality over quantity it was a general statement since the OP mentioned how the program looked short
(which to me means he thought more volume was needed))