Looked up your pit online.
It does look like a nice rig, but I to am a little concerned the firebox is a little small in relationship to the cook chamber and warmer. Here is what I would do:
1) Double check the thermometers!
2) Make sure you have a clean, hot fire. IMO a smaller hot fire is better than cramming it full and choking it down. I start small & hot, build a bed of coals then build it up to the size I need depending on how hot & long I'm going to cook.
3) I would not fret about an hour to get all that steel up to temp. Mine is 24x72 and can take 30-45 minutes.
4) + 1 on what Bludawg & TuscaloosaQ are saying.
Good luck, It really does look like a nice rig, I'm sure you will get it figured out.