My dd has bi-lateral CIs, although she had them sequentially (the first at 20 months and the second at age 7 - she's now 8). I would agree with the posts here about NDCS & CICS - both great sources of information and support. We had a fab teacher of the deaf (who still visits dd in school) who helped me make sense of it all. Yes, I did go through a grieving process - I think this is perfectly normal - but didn't talk to anyone professionally. Looking back on it, I wish I had.
My memories of dd in her pre-school/post-first-CI days was hours and hours sitting at the kitchen table, playing games, looking at books, reading, colouring, baking and all the while talking, talking, talking. At the table we were at the same level, so she was best placed to hear and lip-read. As someone else said, giving a running commentary - but allowing time for dd to respond and then mirroring language back to her.
The ToD used to bring along toys - not special ones for deaf children - but maybe something that would make a particular sound. We had a farm from ELC in which the animals all made noises and the tractor 'chugged'; a small shop when a bell rang when the door or cash register was opened; the ToD used to bring simple jigsaw puzzles or games too, just to reinforce language about colours or shapes or opposites or facial expressions or numbers, for example.
I think the main difference I found with dd was that she didn't 'pick up' language just from overhearing it. It all had to be 'fed in', hence the sessions at the kitchen table. It is hard work. Ultimately, the goal for your friend is for her son to learn to decipher the sounds he hears and to learn to speak. It is important therefore that his family talks to him a lot. 1:1 at nursery should also help. Dd has 1:1 support at school - she attends a mainstream school - and also had this at pre-school. Both environments are very noisy and the support has made a huge difference - she would really struggle without it.
We did lots of going out to everyday places - different shops, zoo, cafes, friends, soft play, school, pre-school etc - I'd take pictures at each place (people must have thought I was mad, photographing the supermarket!) so we could talk about them afterwards, and then use them to explain when we were going again. It's hard for deaf children to anticipate things as they don't always hear the 'we're going to see Granny' or whatever - I had a folder of photos of friends/family/places so I could show dd 'this is who we're going to see/what we're going to do now' so she had some sense of what would be happening during the day.
The above is just a trail of garbled thoughts, so I hope it makes some sense! But please do ask if you have any more questions.