Since it isn't a Monday - Friday, 8-5 work environment, it's probably easier to grant the time off early in employment. I can tell you that in some work environments you would not only have to receive bosses' permission but also overcome some coworker resentment. In many white collar environments, one worker taking time off means others in the department have to work harder to fill the void. People aren't always thrilled to have to pick up slack for the new guy (or gal.) May not seem "right" but it is what it is.
But in a 24/7 medical facility, it isn't nearly as obvious when worker schedules vary.
I'll just leave you with a couple final bits of unsolicited advice. When you finally get that call confirming that you've been hired, make sure you bring up the trips
during that conversation. If the person you are speaking with isn't the right one to approve the time off, find out who you do need to speak with and get in touch with him/her immediately. Don't let it drag out any longer.
And if you meet any resistance over the trips, you really need to think carefully about what is most important to you. Offering to work the holidays + double shifts may be enough to gain approval. However, given that you will be such a new employee, they really are under no obligation to approve the time off.
Nobody likes to lose
DVC points but I think it's worth trading 100 points--and a bit of rest & recreation--for permanent employment. You called the travel agent seminar "a must" but unless travel agent commissions can cover your food, housing and utilities, your full time job is
much more important.
Good luck!