She'll be fine. While this makes perfectly good sense that it might happen, it's actually quite rare that is causes any problems at all.
Your breeder sounds like they know what they're talking about. I'd hold off on feeding today also. What size is your new BP? If it's still a baby and eating less than small rats, I'd actually recommend twice/week feedings and for you to pick a day mid-week for a second feeding day (Wednesday & Saturday for example). If a sub-adult or adult on small rats, weekly feedings are fine.
On a similar note, my personal rule of thumb is also to avoid handling any new arrival until I make sure they're eating well in my care. I wait until they've eaten three consecutive meals without a refusal before I handle them too much.
Have fun with your new BP!