obesebaby I usually get a call the day before ET to tell me arrival time & what FS will be doing the transfer. Embryologist always calls early on ET day ~7.30am to confirm state of embryo.
Over the months I've figured out that our clinic does EPU's from 8.30am immediately followed by ET's. On any given day it's pretty much a sure thing transfer will happen sometime between 9am-12noon. Even though they give a time I usually end up waiting around for a while so essentially have to keep morning free anyway. I wouldn't read too much into it. Their scheduling includes so many variables its rarely accurate. Perhaps your clinic don't like to give an exact time when they know it will likely change?
I find having to constantly be 'on call' a really stressful aspect of IVF. We have our own business & writing the roster is a nightmare! I totally understand how frustrating it must be trying to organise child care. I would just cover yourself for the whole morning & treat yourself to some 'me time' if you finish early. GL tomorrow xx