Phentermine - How long until it starts working?

Today was my first day of taking Adipex .i feel a little disappointed because I REALY did not notice my appetite decreasing. Is it too early to notice anything? I also take 100 mg of Zoloft. Could that be the problem or is it too early ? Please help

Uses of This Medicine
Phentermine is used as part of a short-term plan, along with a low calorie diet, for weight reduction. It is used in obese patients who have not been able to lose weight with diet and exercise alone. Phentermine belongs to the group of medicines known as appetite suppressants.This medicine is available only

Usual Adult Dose for Weight Loss:
15 to 37.5 mg orally once a day before breakfast or 1 to 2 hours after breakfast.

This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

This medicine can be habit-forming. Do not use more than your prescribed dose. Call your doctor if you think your medicine is not working.

Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.

Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.

Call your doctor right away if you notice any of these side effects:
Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing, Chest pain, fainting, trouble breathing,Fast, slow, pounding, or uneven heartbeat,Seizures or tremors
Severe headache, Swelling of your feet or lower legs
If you notice these less serious side effects, talk with your doctor:
Changes in sex drive,Dizziness,drowsiness, mild headache
Dry mouth or a bad taste in your mouth
Nausea, vomiting, diarrhea, constipation, stomach cramps, Restlessness or nervousness, trouble sleeping

If you notice other side effects that you think are caused by this medicine, tell your doctor.

Hope this helps!