Hello, Thank you for asking your query at DoctorSpring.
Yes, you should be expecting your period in the fourth week or in your placebo week. First thing you need to understand is every women metabolism is different, therefore even menstrual cycle will vary. But, usually most of the women start their period in the placebo week or free pill week. As this is the first time you are using a pill, you may just spot or may not have a period at all. Your body system takes 3 months or more to adjust to the hormones. Therefore, after usage of 3-4 weks you will understand the pattern your body has settled into. You will be able to predict when you can expect your period.
Hope this helps. Please feel free to ask follow-up questions.