Hi just my first home loads myself , I can only tell you what I've done , I used once fired federal brass , I left the length alone re-reamed the primer pocket and chamfered it , chamfered the inside of the flash hole , resized the neck and chamfered the neck inside and out , used CCI small rifle primers , load Vit n133 in 5 offs in .2 stages from 22 gr up to 24 and used Berger 52 gr flat bottom target round seated to make the o/l 54.25 to 54.3 which is .1 under maximum, I'll be at the range next Friday to fire the 22 to 23 ones I'll post back with my results

As far as trimming the case length, I usually subtract 0.005″ from the maximum length number and trim to that.

Hi here you go 22.8 looking good 5 shot group done at 100 meters at the yorkshire shooting club , 4 touching and a flyer which could/is down to me

As long as the case is shorter than recommended max you will be fine, consistent case length is more important for accuracy than a particular length.  Annealing your brass will also help keep uniform neck tension.