Challah

Question

I love to bake my own challah. For years I have been using a recipe that does not have enough flour that you need to take challah before baking. I have just recently received this amazing new recipe and you have to take challah before baking. When you take the challah I know you are not allowed to have anything else in the oven when you are burning it. My question is do you have to burn the challah right away or can you wait until you have made a few batches and burn them all at the same time? Thank you for all of your hard work.