I work for a large company and I too think that is somewhat of a disadvantage when it comes to vacation time.
We have a department of about 50 people. We hired a woman 2 years ago in March who never mentioned anything about vacation time prior to being hired. After she was on board, she then told us that she had paid for a cruise the week of July 4th. Well, that's a pretty popular week for vacation and we already had a whole bunch of people off. Additionally, there were some folks who had requested it even before this other woman was hired and been denied because we had reached our limit for people off that day. I know it sounds mean, but we had no other choice but to say no. It wouldn't have been fair to the others that had requested it and not received it for us to say yes to her. She had her choice of cancelling her vacation (which she eventually did) or going anway and being put on probation or possibly being terminated for taking unapproved time-off. If she would have asked on her interview, we probably would have told her up-front that it was going to be a problem and she could have made the decision then whether the vacation was more important to her than the job.
I know it's not what you want to hear, but I can guarantee that if somebody was requesting more time than was earned in the year, we'd say no. Saying yes would set a precedent that I wouldn't want to deal with in the future. Your wedding may be just as important to you as a "once in a lifetime" trip for somebody else. I'm reminded of a woman who did quit because she worked on the side in a theatre company and got a "once in a lifetime" opportunity to sing in Italy for a month. She wanted the time off, unpaid, but we didn't approve it. As a manager in a large company, we don't have the authority to make the call on what's "more important" to one individual vs. another. The only factor we can use is how it affects the company and how the policy is being used (i.e. if one person gets unpaid time off in excess of what they've earned, everybody get it regardless of the reason - unless it's covered in another policy, such as disability leave).
This is one of those "hope for the best, but be prepared for the worst" scenarios. Good luck to you and congratulations!