When you hire a vendor, sign a contract and leave a deposit you are tied to a vendor but that doesn't mean the ideas you discussed are the final ideas for your wedding. You have the option to change your mind on your theme and colors and wedding details up until about a month or so before.
Your wedding cake will not be made until the week of your wedding. The flowers won't be ordered until 2 to 4 weeks before. So it's okay to keep looking at wedding blogs and magazines to find new and interesting ideas.
When you schedule appointments with your wedding vendors bring all of your ideas with you - especially photos - and let your vendor help you pinpoint what your wedding will look and feel like. You don't have to use every idea - some may be good for other wedding-related parties or future occasions. But keep looking for inspiration until about a month before your wedding. Remember that when you send your wedding invitations out they will show guests your theme and colors and give them an idea of the look and feel over your wedding, so at that point it's just a few details you can tweak you can't really go back to the drawing board with a whole new concept.