In most healthcare facilities (hospitals or EMS), the principle is quite clear: working time begins when you are at the employer's disposal. And that includes being already changed if the uniform is mandatory and you cannot wear it from home. It is not a minor detail, it comes from Swiss labor law and common practice in internal agreements and regulations.
Simply put: - If your shift starts at 07:00, you must be operational at 07:00. - But the time necessary to change, if it is mandatory to do so at the center, should be included in the work time.
Another thing is the reality of day-to-day life, where many teams operate with that "cultural pressure" to arrive early, change quickly and be in rapport at 07:00 as if it were normal. It happens, yes. But it does not make the practice correct.
Furthermore, it depends quite a bit on the canton, the hospital and the agreement (CCT in some sectors). In large public hospitals it is usually more regulated. In small or private EMS, more "flexible", to put it mildly.
So yes, Swiss punctuality: totally.
But punctuality does not mean starting to work for free for five or ten minutes every day.
And this, for someone starting a job, is key to understand. Adapt to the system, yes, but without normalizing things that are not normal.