I appreciate your query.
Basically, Sysron is progesterone
You can take any of multiple brands available on the market
As long as you take progesterone, you will not have your periods, and then after stopping the pills, you will normally have your period within 2 -3 days, maximum within a week.
However, I should tell you that after progesterone withdrawal, you might have a heavier than normal period.
Also, unless it is absolutely necessary, there is no indication to meddle with a normal menstrual cycle.
Understanding that , if you wish to delay your periods - then , you should start taking progesterone from 15th december.
Earliest that you expect your period is around 22nd december.
So start the pills from 15th december, and keep taking till, say 25th december. Once you stop them, expect bleeding within 2 - 3 days.
For the exact dose, consult a gynecologist, who will prescribe the pills based on your body weight and other risk factors.
All the best.