Hi Melanie!
Generally, if you don't provide a proof of time, you will be in one of the later (or last) corrals. If you want to change that, you can go to the Runners Relations booth at the expo with your proof of race time. It needs to be a 10K or higher. If your time qualifies you, they will put a sticker on your bib with your new corral.
You can find corral placements on the runDisney website. It is based on your race number. The race numbers can be found on your waiver. To find the waiver, go to the
Princess Half website, then click on the RUNNER INFO tab, then Waiver. Right above the waiver link is the Corral and Bib Assignment link that lists corral numbers.
However, I have started in about all of the corrals. Starting in the last one has never bothered me, and I actually enjoyed being in a more laid-back atmosphere!
Either way, you will be fine!
Please let me know if you have any other questions.