The shortest honest answer is: one month minimum, and judge at the end of it rather than in the middle.
Why one month
Our preparations are taken two or three times a day and work gradually. A week is rarely long enough to tell whether anything is changing. Most of our kits are sold as a one-month course for exactly this reason, with two- and three-month packs for people who want to continue.
Timing matters
Some drops are taken before meals and some after — it is printed on every product page and on the bottle. External items like oils, sprays and ointments are usually applied twice a day.
When to stop
Stop and speak to a practitioner if you notice any discomfort, if your symptoms are getting worse rather than better, or if you start a prescription medicine for the same condition.