I get it: You're coming to the end of the due diligence cycle, all the terms are settled, and now you're wondering if you can get the acquiring company to give you a vacation before you start.
Running a startup is hard, and running a startup while doing due diligence and pretending nothing out of the ordinary is happening is even harder. A vacation seems more appealing than ever.
In most cases, you can't immediately take a vacation: Most employers like Google start you off with 0 days of vacation, each payroll cycle you get extra ~0.288 vacation days, and you can't go too many days into to the red. For these acquirers, you could negotiate a vacation between close and your start date, but I've never seen that happen in practice.
In some cases you can: For example, Twitter has an as-needed vacation policy without a preset limit, so you could argue that right at the beginning of working there, you need a vacation.
If you can take a vacation, when should you?
As hard as it sounds, you should start your new job and work hard for at least a month: You just got your TechCrunch mention, and everyone at the acquirer's company is curious about your team and what you can bring to the table. You should use the time in the spotlight to get to know your new coworkers, and show your new manager that he or she has done the right thing in sponsoring your deal. As the former CEO or COO, you'll also receive a ton of requests from accounting and finance to explain your balance sheet, and your attendance will be mandatory.
After a month or so, you've met everyone and now you can use the fruits of your labor to pay for a nice vacation.