Applying to switch from Ed.S to PhD the first semester?

[VygotskyLover]

One of the schools that I have been accepted into for an Ed.S allows a "fast track" option for students who decided they would like to earn a PhD instead. I've thought about this a lot, and when I first started applying to schools last year I wasn't sure if I could handle a PhD program. However, going through this entire graduate school interviewing process, I feel like I have gained more confidence in my abilities, and I am more than sure that I'd be much happier in a PhD program. I know I have the option to wait until next year and reapply as a PhD applicant, but that seems like a complete gamble that I just don't want to take. 

My main worry is that I don't want the school to think that I never had intentions of being in the Ed.S program if I apply to switch too quickly. Does anyone have any advice on this? Is there a proper way to switch over with the least damage to my reputation as possible? 

[GradSchoolTruther]

You might want to to check on whether you have to be in the program for a year before you switch. As for your reputation, if it's the same department, don't think many people would care you'd like to pursue a Ph.D.