Typical of non Texans to get Denton confused with Denison. It's about 55 miles away from me. This might be a little more convenient, but I have a LONG way to go before I can be able to perform this level of music again. I'm certain that my embouchure is not what it once was. Then there's the reading practice, etc. I suppose that I need to acquire an Arban's.
I fled Texas in 1982, never to return. Lucky me!
You know, I was actually thinking Denison, but figured I was wrong. So much for second-guessing myself!

Trust me, Rob. Most community bands are outfitted with enthusiasts who pull their horns out of the case once per week, whether or not they actually need it.

You could get up to reasonable shape within a couple-three weeks. Just play some long tones and flexibility exercises. The long tones will restore some tone quality and the flexibility work will develop chop strength.
I can scan some stuff out of my own Arbans and send it to you if you'd like. I wouldn't buy a copy, unless you pony up $60 for the updated version edited by Brian Bowman and Joseph Alessi. Alessi is the principal trombonist with the NY Phil. It's a much better book (that actually lies flat) and it has virtually all of those 100 year old mistakes corrected.
ETA: Reviewed the Sherman Orchestra site. Yeah, I'd stay away from orchestras for awhile. The wire choir tends to run things and you know how THAT goes! (Besides, who wants to count hundreds of measures of rest at every rehearsal?)
You've got no community band in Denison?