Just because the bride is getting married next year, doesn’t mean you have all the liberty to delay her order so you can accommodate other clients who need their dresses done by the end of this year, especially if you have already stated in your contract that you will deliver your service by the 3rd week of October. It is not for you to decide how much extension you’re going to give yourself, because 1) the bride must have booked you early because she didn’t want to be cramming 1 month before her big day; 2) it’s not the bride’s fault if your other clients booked you at a later date for a rush order, so you technically don’t have the sole discretion whether or not you should put her needs at the bottom of your to-do list and; 3) the bride signed up for your service because she counts on your fixed due date of delivery, and not a due date that comes with an extend-all-you-can feature.
There’s nothing wrong with prioritizing things. But the fact that the bride entrusted you with that certain task months before her wedding and you’re not respecting her timeline means that you’re recklessly and inconsiderately putting aside one of her top priorities. And it’s not fair.
It would’ve been forgivable if you didn’t settle on a delivery date and signed a contract; problem is you did, and you have no choice but to perform and deliver what’s expected of you.
Unless you highly look forward to becoming another pain in a bride’s ass...