If you either finish the checkout process for the $30 plan it will add the discount or it will add it after activation of the new card. If you have a watch you are adding with your iPhone that will add $5 to the bill. Once activated your account should say valued member discount and will be $25 unless you are selecting the plus plan.
You will not lose service until the card arrive and you start the activation process and remove the card, at that point you will not have service until the new card is activated. Took me less than 5 minutes.
Your billing will not change, once activated if it still shows $30 with no discount you will need to contact customer service and have it fixed.
