Is it generally possible to book award nights on the same-day as check-in? If a property shows award nights available well in advance, is it fair to expect those nights to still be available the day-of?

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Later this month I'll be driving from San Francisco to New York for a new job. My prospective employer will be reimbursing most expenses, but I figure I'd apply for the IHG Mastercard to offset some of the lodging expenses with award nights. I'd much rather put some of that reimbursement towards temporary housing for my first month on the job.

I've briefly sketched out my route and am vaguely aware of where I should expect to be for each night of the trip. That being said, I also want to account for any unexpected circumstances and don't want to book nights well in advance.

For example, suppose I was planning on getting as far as Elko, NV one day but decide to stop early in Winnemuca instead. Could I call the Platinum line and make a rewards booking a few hours before I arrive?

Any other tips on maximizing IHG points on a cross-country trip would also be appreciated. Thanks in advance for your help.