I try and loose jump once a week. To warm up I let them off in the school and get them moving, then start putting out poles and let them go through then build up to jumps. I don't have a lane so have to build it as I go so they are usually warmed up by the time i've got the fences up. Then they cool of as I put all the poles away again. I'm normally more out of breath that the horse!
I'd warm up on the lunge to settle her down and get thc tickles out of heels in a "controlled" way...then pop some poles on the ground to lunge over (both reins) and then let her go to carry on working on the flat off the lunge, then start to add a few fences.
just try as best as possible to keep it all calm. If she pisses around I just ignore her and she soon stops,
I'd probably do it maybe every 2 weeks? only because time flies so quickly and I don't realise how much time has gone!