I feel like Guest service doesn't have much of a routine it's kind of do what you can on the time you got left, ususally I open so I clean up the leftover reshop from flow and the night before and make sure the desk is looking clean and presentable, set up salvage boxes if they were taken the night before, start over in bullseyes and get the reshop and pulls done before it gets busy. Make sure you have all your equipment, such as walkie, PDA to audit and maybe a mydevice if you get lucky. Sometimes I go through RFID and make sure that's either defected out or a tag is created. Go through the boxes of holds and paid and left to see if any needs to go back to the floor and so on.
When ever I open that's the kind of things I go thorough, there isn't much of a routine just kind of clean everything up from the day before so you can be productive and ready. It's just to make sure I have the materials that let me do my job efficiently.
With closing for me it doesn't happen as often but we make sure salvage and CRC are ready to be boxed up for the night, we close them if they are full and go down the list for CRC to make sure we got everything, go through our online order log book to make sure every order was processed and charged. Zone and reshop bullseye when it gets super quiet and make sure it looks good for either flow or the opener. Also maybe go through RFID if you have time so it doesn't pile up. Make sure you have the essentials, tape, staples, receipt paper, registry bags, regular bags, pens, highlighters.
When I close I kind of just straighten things up to make it looks presentable and not leave much clean up for whoever is coming in the following morning.
Sorry for the ramble just there is a lot of tasks to do at guest service so it's a good way to just know what to do it