When the weekend or whatever is over, you go back and take the placebos so that you have your period. This does not affect the effectiveness of your birth control method. You should consult your physician before attempting this. You need to make sure it is safe for you to do it. You also need to figure out which pills from the extra pack you should take.
Different brands have different formulations.
Some vary the hormones levels as the month goes on. You should check with the clinician to make sure you take the correct pills. You also need to check on how long it is safe for you to delay your period. Plus you need the extra pack. You should always have full pack as a back up.