First of all (((hugs))), and congratulations on your new LO
As hard as it is, I would try very much to focus on enjoying these next couple of weeks with your LO at home rather than worrying about what will happen once he starts with the nanny. He is so, so tiny still, honestly true independent sleep probably isn't even possible at this stage. And if you try I think it's likely that the next two weeks instead of being fun will become stressful and exhausting - not what you need. If the nanny is going to be looking after him several days a week she will need to find her own ways of helping him to settle and soothe himself as he grows and develops - and it's perfectly possible for LOs to learn different ways of sleeping in different contexts. My LO is older but she will be rocked or have her back rubbed to sleep at nursery, whereas she is a totally independent sleeper at home. If you want the nanny to avoid particular things e.g. bottle to sleep then that's something worth discussing, but in terms of environment and sleep associations then at this point LO will not be set on particular routines/associations so is at a great age to learn to settle in a new situation.
How are you trying to settle LO at the moment at home? Have you tried shh pat? I'd maybe try one nap a day in the crib if you are really keen to start some independent sleep habits, using shh pat if needed, but just take the other naps whenever and however for now. At 7 weeks DD was rocked, held, bounced, pushed in the pram or in the car for all naps - I don't honestly believe these things become fixed as props until a bit later on - and they are not hard to tackle with a bit of consistency once LO is a bit older. It's all about survival and getting to know your new arrival in the early weeks
Hope that helps a bit, or at least provides some reassurance.