There is some sort of unwritten rule which I haven't received the memo for that the coffee shop should be open a good 5-10 minutes before schedule. Customers often ask "When are you opening?", "What time do you open?" or "What time are you opening?" typically with a follow up huff and a puff just as we are opening on the exact minute we are scheduled to.

Essentially we are opening at the exact time on the sign, unless for unforeseen circumstances beyond our control where we cannot open in time. There may be occasions for a soft opening just a few minutes early.

As a customer it is annoying and frustrating if a shop isn't open or opens later than stated... but there is no legal requirement for that shop to even be open, just a poor business judgement to not honour the opening hours advertised. If you need to buy something immediately as they open, either you should have purchased whatever that product is yesterday or before, or if it is a serviced based offering, you don't really have time. Even when the doors are open, till service isn't typically immediate anyway.