Hi Middymum,
Sorry to hear about your partner's diagnosis. I hope he makes a full recovery.
I can't really help with the process of already frozen sperm but have just completed my first full IVF/ICSI cycle so hopefully what I know can help you.

As your partner has already got frozen sperm, I'm not sure what is done here in terms of when they thaw some for fertilisation. My husband's sperm was collected on the day of EPU to be fertilised through ICSI later that day. So imagine if you were wanting to do a fresh transfer, they would thaw some of his the same day.

As for what happens after EPU, if you wanted it / have no health problems / and of course you get suitable embyros, you can have a fresh transfer 3 to 5/6 days later depending what your clinic does or advises. I had a 3 day transfer as my embryos weren't looking very good. A 5 day transfer is generally what most clinics aim for. With our clinic, any that don't get transferred at day 3 are continued to grow until day 5 and those that survive to day 5, are frozen. Of course if you've had a day 5 transfer, then any remaining that are suitable for freezing, are frozen that day. If you get the opportunity to freeze an embryo(s), they thaw them first before transferring them back. I'm not 100% sure, but imagine the thaw / transfer is done on the same day. We got nothing to freeze this cycle, so will have to do another stimulated cycle (i.e. full IVF/ICSI cycle). The transfer itself is not under any anesthetic (well wasn't for me) and only takes about 5 minutes.

All the best. Take care of yourselves.

Cheers
Zig.