Hi there,
I've just been through this with my DS - funnily enough, he's exactly the same age and was also doing two mornings a week, and had never been away from me.
I'm not sure there's anything you particularly need to teach him (Though, will he be having meals there? At DS's preschool they're quite big on things like only using an open cup for drinks, and having to use a knife/spoon/fork instead of fingers for lunch, neither of which I'd done all that much beforehand. So, if he will be eating there, it's worth finding out what the 'rules' are, because these are the sorts of things you can try to prepare him for.)
Apart from that, I can give you a few thoughts based on my own experience (apologies if I go on too much, but this still looms pretty large in my mind).
- It is likely to be quite difficult for you as well as him. The first few sessions, the thing I found hardest was not to cry in front of him when he got upset, which is obviously not helpful. Not sure how you avoid this, but I think maybe I'd have found it easier if I'd known quite how much it would upset me beforehand!
- TRUST YOUR INSTINCTS. I was advised to leave DS 'cold turkey' at the first session. Deep down I knew this was wrong (for him), but I trusted others with more experience. In the event, he became totally hysterical, and I really believe it set us back considerably. I ended up having to stay for the whole of the first 4 or 5 sessions after that, because he was so inconsolable otherwise. What I should have done is stayed with him for the first couple of sessions (and told him that I was going to stay), so that he came to see nursery as a positive experience and got to trust the staff and know the children, without also having to deal immediately with the stress of being without mummy. I'm not saying this is right for every child (my DS is extra-sensitive), but my point is that YOU know YOUR child better than anyone else.
- I found that the single most important thing was DS forming an attachment to one of the members of staff. The reason he's pretty settled now is that he feels I'm basically transferring him from my care to hers. Not sure you can do anything to force that to happen (and it's important that he chooses who he's going to bond with), but just thought I'd mention it as it's made such a difference for us.
- However hard it is to start with, it doesn't mean it won't settle down very quickly. After the first couple of sessions with DS, I was seriously considering abandoning the whole experiment because he was SO upset. But actually, it only took a total of about 3 weeks for him to be ok, and 4 or 5 weeks for him to be really pretty happy there. There's still the odd wobble, obviously, but he now goes off perfectly happily in the mornings, and is really full of what he's been up to when I collect him, and we're only 7 weeks in .
Just reread your question, and it was mostly about practical stuff - sorry! But I really don't think there are many 'standards' he'll have to meet (DS is totally lazy inexperienced in dressing himself, for example). Oh, and DS is still in nappies too, and that hasn't been a problem. Personally, I wouldn't try to potty train him too soon - nursery will be enough of a pressure on him without trying to do potty training at the same time.
Re saying that mummy won't be there, I'd definitely be honest. Tell him you're staying with him for the first couple of sessions (if that's what you're doing) but that, after that, you won't be. I used to make a bit of a joke of it - 'of course MUMMIES don't go to pre-school' (along with 'of course DADDIES/GRANNIES/ELEPHANTS don't go to pre-school' etc).
Oh, and expect him to be knackered. The only downside of having a morning to myself is that the afternoon is total nightmare because DS is so shattered and sort of strung out.
Sorry, I've rambled. Hope it helps.