Question/Poll: When planning on booking a vacation do you A) Look for the vacation then see if the dates are available for you to take off from work before booking the vacation or

Book the vacation, put down a non-returnable refund, and then see if the dates are available to take time off work.
I ask this only because - after putting in for and receiving time off from work from my boss, a new co-worker responds to the department wide email that goes out stating i've been approved for that time off so FYI to others not to book that week with a 'Hmmm hope that's not the same week I just booked my non-refundable hotel for.'
Have I done it backwards all my life by seeing if the vacation time is available before booking the vacation?