AITAH for refusing to come to work early when my new manager wants me to

I work as a beauty therapist and at my company so I give women facials and also build a care plan for them on what sort of products to use to keep their skin healthy and for me to do my job properly we are give 15 minutes of prep time before each client to get our station ready and sort everything out.

well recently our manager got replaced and the new manager has gotten rid of our prep time in the morning because during that prep time "we aren't making money for the company so we shouldn't be getting paid for it".

So I thought okay she just wants us to arrive when the client does and make them wait in the waiting room until we are ready. But when I did this yesterday she wrote me up for making the client wait and saying if I can't start right away It's my problem and I need to come early.

So the next I came 15 minutes early and clocked in when I arrived and began work as normal. Well this may not surprise you guys but halfway through the shift she wanted to talk to me and said I'm on thin ice for deliberately going against what she said. So I asked her to clarify and she basically wants me to come to work early and do the prep time for free, comparing to getting dressed and driving to work saying we don't get paid for that either.

But I've decided I don't really want to come early to work and not get paid for something I used to get paid for. Is this sort of behavior normal and am I being an asshole here or is my new manager just trying to take advantage of me and my coworkers