I've been in Reception for 3 years, so while not massively experienced, I know the ropes! My partner teacher this year has just moved down from Y6.
This week has been so stressful. She has changed nearly everything without asking me and has set up things without telling me- for example, preparing special keepsakes for her class to take home on the first day. She has also arranged a whole new buddy system. Before, we had a rota of Y6s who would come in a group of 5 or 6 to help at playtime and at lunchtime. It worked well. She arranged (without telling me) for every child to have a designated Y6 buddy.
It was well meaning and I know the theory behind it, but it also meant that we had 60 extra big children to deal with in our corridor and playground, as well as in the lunchroom. The Y6s are well meaning but they overhype the littlies, and they couldn't follow simple instructions like 'take your buddy back to the same seat', so there were jackets and snacks everywhere in the lunch room. It was also far too noisy and intimidating for them. They're too small.
To top off the week, she then arranged for her class to have a paired reading session with Y6 and gave them all cakes and juice, took pictures and posted it on the school Twitter, which was the first I knew of it.
I don't know whether to message her and ask her to make time for a chat on Monday, to email her with my concerns or to just ask to speak to her on Monday morning.