Quickest way to either mop this up or get it early is to start a new game on Central Perks 2.0
Go to the first roll-call and then go straight to the showers. (Take the south-west stairs from roll-call area and it the first door you pass upstairs)
You can sit there using the shower and miss everything until roll-call at the end of the day as there is very little activities to do and no Midday roll call.
Achievement bar tracker goes up about 20% per day and only goes up when you leave the shower not during it.