Time melatonin for a new schedule.
Melatonin used to move a sleep schedule earlier works as a timing signal rather than a sedative, so it is taken well before the target sleep time — commonly two to three hours ahead, with low doses taken earlier. The schedule itself moves gradually: shifting bedtime by around half an hour a day is tolerated, so the number of days needed follows from the size of the shift.
Melatonin timing
Take time = target sleep time - lead hours (3 h for doses up to 1 mg, otherwise 2 h); days to shift = minutes of shift needed / shift achieved per day
Melatonin is a regulated medicine in some countries and a supplement in others, and it interacts with anticoagulants, immunosuppressants, epilepsy medication and contraceptives. It is not recommended in pregnancy or for children without medical supervision. Consult a healthcare professional before use.
For advancing a delayed sleep phase, a low dose two to three hours before the target sleep time is the usual approach. Taking it at bedtime treats it as a sedative, which is not how it primarily works.
Not for circadian timing. Doses of 0.5-1 mg are typically as effective as much larger ones for phase shifting, with fewer next-day effects.
Around 30-60 minutes a day is realistic. Larger jumps tend to fail because the circadian clock and light exposure lag behind.