Disappointment in new horse?

My gorgeous girl was delivered last night.

I own another 3, Loaned 2 also.

Last night and all day today I felt positive.

Today I've gone into her stable to groom her and as soon as I moved beyond the withers to groom her rear end, it felt like it began to go wrong.

I was expecting a reluctantance to lift her hand legs as this was mentioned in the vetting (but the vet said she came around fast), not a hatred of grooming.

She backed up from me fast, ears pinned and leg up, span in the stall to get away.

Im suddenly feeling disheartened about buying her and have been trying to think back to grooming my others for the first time.

I will be fair. 2 were 6 months old and terrified but that's okay as they were babies. I don't remember the first groom of my other girl.

I know I'm just overthinking because I wanted to have this instant connection.

Tomorrow I plan to lunge her, and the day after try to have a ride in the school.

I may try to groom her outside her stable instead.

Can you tell me the stories of your first days with a newbie to make me feel better and remember this is a slow process and the bond will come!