One works early morning to afternoon (say 7 AM to 3 PM) and the other comes in 11 AM to 7 PM. So for several hours during the day, they overlap. The later time receptionist is also chronically late by a good 10-15 minutes, sometimes even 20 minutes EVERY day. The early receptionist says nothing just stays polite and professional and covers for her. Then the late receptionist decides her makeup needs doing or hair needs brushing and disappears for another 10, so she's not really officially ready to start working until 11:30-11:40. This leaves the first receptionist, who comes in a good ten to 15 minutes BEFORE 7 AM to come in, get the office lights on, papers picked up, etc.and ready to answer phones online at 7 AM to work alone another 40 minutes when late receptionist is already on the clock to be working. The chronically late receptionist takes long breaks throughout the day, disappears to make multiple phone calls or have Facetime with some friends and family at all times throughout the day, almost every day, or spends her day scrolling her phone barely looking up to answer the phone after every 10 the early receptionist happens to pick up, so the early receptionist doesn't "fuss" and just picks up the slack, answers email, and gets "told" what else to do by the later receptionist who seems to pick and choose what she will do if it's too complex she hands it to the early receptionist.
Here is the dealbreaker: The early receptionist has her reminder set to go off five minutes before her shift ends, to remind herself to start shutting down for the day. Five minutes gives her time to go to the bathroom, tie up what she was doing on the computer, shut down the computer and put her coat on and pick up her purse.
This seems to bother the later receptionist who is always chronically late by 10 to 15 minutes every day, and has become passive aggressive by outright disappearing when it gets close to departure time despite being told by later receptionist that it's about time for her to go.
The early receptionist has tried to meet this chronically late receptionist halfway by setting her reminder 15 minutes prior to help the later receptionist in case she needs to get her own ducks in order (go to the bathroom, get a water, stretch her legs, etc.). But with the understanding the later receptionist will be there to cover when the early receptionist leaves, usually about two minutes to three minutes before her shift ends. This didn't work and the late receptionist just shrugs it off and says you have to go, go.
Today it came to a head as she disappeared for 40 minutes. No one was around to cover and the early receptionist stayed put because there was no one to answer the phones. The late receptionist strolls in her coffee and asks, "What time is it?" The late receptionist up to this point had not been called out for her chronic lateness or overall lack of professionalism.
If you were the early receptionist, what would you do?
Is being 10-15 minutes late every day better than leaving 2 minutes early?
EDIT FROM ANSWER
This is in New York City, USA. The later receptionist is playing games and spends a lot of time NOT working as well as being late every day. But this ONE thing, is the thing she wants to focus on, never mind the early receptionist is covering her on EVERYTHING.
There are lunch breaks, and the late receptionist makes excuses not to go out saying she's way too busy and tries to get the company to pick up her tab for lunch! She complains about things a lot at work and the early receptionist just politely listens. Ironically, the late receptionst talks about not letting these people take advantage of you, yet she does the same thing!