When to tell potential employees about upcoming large family vacation?

EDIT: Employers. Sorry, typo. I am interviewing for a few new jobs. Hopefully, but the end of this month/beginning of next I will have a new position. In the meantime my parents have booked a 15 day European cruise for the whole family. A grand family bonding experience, if you will. It isn’t until August but I’m worried about how this will effect my ability to get a new position or whether I should even mention it before getting an offer.

For reference I’m in the US in the hospitality industry.

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