Tbh for newcomers, the confusing part isn’t opening the vial; it’s what happens afterward. A common habit is to write the date on a sticker and treat the calendar as a prompt, not a rule.
A 30 mL vial can look fine for weeks and still be past someone’s comfort window. Ours gets a tape label and stays out of light; at 19 days it’s still in rotation, and around 28 it gets a fresh look.
The check is boring: date, cloudiness, specks, storage, and whether the last few uses felt ordinary. No forum post should settle that for you. If it seems off, out it goes.
Sticker, calendar reminder, or memory — what does your actual routine look like?