I agree with @kmakm to be ready for anything so you don't worry.
I had caps and scarves and a wig all ready when I first went bald. I have lived in scarves since then, never taking to my expensive wig.
I imagine you have lots to do and cope with in preparation for a wedding on top of starting chemo. You poor dear, life can be crazy sometimes can't it. I'm sure you will be beautiful whatever happens.
I had my mum's funeral not long after I went bald on AC. I wore a scarf and people were lovely about it.
I think a lot of coping is just having a positive attitude! I've had lots of compliments on how I look in scarves and a bit of makeup. I think people are surprised that you look healthy in cancer treatment!
I've just checked my photos for the timing of my hair loss (I'm Her2 as well and had AC and then Paclitaxel).
My hair held on quite a long time, I didn't shave it off till one day before three weeks after my first AC, so day 20. I think it started to look a bit thin a little before that but I attended a Look Good Feel Better session 17 days after my first AC with hair, I wasn't quite ready to brave the world with none! It was good to see others in the session bald as they were all beautiful and brave and I felt less alone about the transition.
I had dose dense AC - fortnightly - so I'd had a second infusion 13 days after the first, my hair was looking thin day 18, I shaved it day 20. Good luck with it all!