My Nan has an MBE and my FIL has and OBE. And we are the most regular working class family there is. My Nan got hers for services to the charity she set up as is still running 55 years later, my FIL got one for something he did related to his work (not military but took a job supporting troops out in Iraq during the Iraq war).
If I remember rightly, they both got letters informing them they had been selected, but were not allowed to tell anyone until the actual birthday honours were announced. There was a few months between the letter and the announcements. Amazing that my Nan managed to keep it a secret!
Then the actual ceremony, both my Nan and FIL were told it could either be the Queen or Prince Charles I believe, but both had the Queen do them (years apart). There is quite a gap between the announcement and the ceremony too, I think they could have 3 guests attend with them (this was obviously pre-covid) and you had to give all of their details months before so they could do checks on every guest attending.
With my Nans one, my Grandad was too unwell on the day to go, he couldn't manage the car journey and it is a long day. But because of the checks needed, none of us could go in his space.
If your friend does get selected, tell him to start saving. The video and pictures you can purchase are £££. We paid for my Nan's as a present, and I'm glad we did as they are lovely photos.
Fingers crossed for your friend!