To be honest, I'm not sure I'd recommend all of this manipulating of our cycle. If you are intent on doing so, all you can do is follow your doctors advise. But break through bleeding can and will happen to many women when altering their hormones. It's hard to predict when and if it will happen. I'm sorry I don't have better news for you.
Why you want to delay your period anyway?
There are many reasons a woman would want to delay her period. Some conditions are worsened by menstruation, such as endometriosis or anemia. Other reasons: a beach vacation, a wedding, and about a million other reasons why. If you are looking to regularly miss your period you need to have a good convo with your OB/GYN. As to which medication will have the best results in a large part depends on your body. Since these are prescription medications the best resource would be the prescribing provider. I would be prepared to discuss what benefits you are looking for. Are you looking to skip a period for a one time event, or are you wanting to delay your period on a regular basis? Those questions will help your healthcare provider come up with a plan that will work best for your body and your desired goals.