Sorry if I've worried you, and overall I'm sure your ds will be fine. Mine settled into nursery very happily and really enjoys it, I'm sure you will have just as good an experience.
Ds was almost 7 months and was certainly old enough to tell the difference between me and another carer. And when I'd left him (briefly) in a creche to go to the dentist's they'd phoned to say I'd better come back as he was upset (although OK by the time I did reach him).
I'm doubtful about the 'babies don't have separation anxiety so you can just leave them with no preparation' line, if that's what your nursery are saying. Sure, the visits are for you to get used to it as well, and that's important because babies will pick up on a worried mummy. But even tiny babies recognise their mother's smell, face (OK, hairline), voice. 'Separation anxiety' as a defined phenomenon may come later, but that doesn't mean small babies can have a complete change in environment and carer with no preparation, IMO. Saying that 'separation anxiety' starts on the dot of 9 months or whatever is a bit like the crude definition of 'bonding' that you get in some hospital where they will say 'oh, we don't take the baby away from you immediately as you need time to bond' as if establishing a relationship with your baby is something that takes place in the first 10 minutes and is then complete.
Certainly briefing them on your ds's routine is important to make him feel secure, and it's a good sign that they recognise this. But if you have time before you start work, I would recommend you both spend a little time in the baby room, and then leave him in the room but be on hand if you are needed. I'm sure you won't be, but it helps!