Hi Bertie,
I just had some good advice from a lovely health visitor on this subject! My son is 2.4 and I'm due in 11 weeks so similar situation too.
She thought a hospital visit was nice if you are feeling / looking well and up to it, and it reduces the time they go without seeing you.
But her main tip was that wherever you are when he first sees baby, when he comes in, don't be holding the baby - have your arms ready to receive him and make a really big fuss that he's there... I asked if dad should hold baby and she said no, put the baby in the cot/basket and after a few minutes of chatting with your son, casually say something along the lines of "shall we have a look at this baby then?" This approach reduces the chances of resentment apparently and she gave me two other good tips:
Not to refer to your son all of a sudden as "the big boy" (I would instinctively have done this otherwise!), because for the past two years he's been your "baby" and to suddenly lose that place is hard. She said if yu want to say something like this then try "special" or "lovely" boy instead or similar.
2nd tip was that if/when people bring a little gift for your son as well as for the baby, put a few aside and when you are feeding baby, he can snuggle in and open a present, then turn this time in to a story for him - so he has positive associations with you feeding the baby.
This will be interesting as I seem to remember needing all my arms for b/f'ing the first time but will def. be giving it a go.
My friend also asked people not to "coo" over her newborn too much when her toddler was in earshot.
I'm hoping these approaches will sow the seeds in the early days to reduce resentment/competitiveness and I won't have to do them for too long, we'll see! Hope some of this helps you too.