Good luck congrats and everything !
There is only 20 months between my two boys, and we were concerned how DS1 would cope with the new arrival - used the age old tactic of bribery and got a teddy that DS2 had 'brought home' with him from the hospital, went down a treat !
MIL thought I was mad, but I also bought a newborn doll ( DS1 was mummys little helper from an early age!) so that when I changed/bathed/dressed He could do the same with he's 'baby'
Lasted about 3 days before it got left in the toy box

but 'cos we'd 'played babies' together he saw it as a bonding thing beetween us rather than mum spending all her time with baby.
Just don't leave the doll naked on the floor in the lounge over night, it totally freaked hubby out 6am when doing the usual sleep walk to the kettle - I can still hear the screams now
After a couple of days I had no problems BF DS1, though at about 8 weeks he got topped up with a bottle but still had the majority as BF ( despite being told that if I started on the bottle he's not want the breast) I eventually had to stop at 8 months cos he grew teeth and after 2 really good bites I couldn't relax enough) However DS2 was a nightmare would never settle and ended up with 2 days BF 3 daysbottle and would flatly refuse the other!!! I had to stop eventually as I was either too 'empty' or too 'full'
So I guess what Im trying to say is you never know how it'll be each time as the little darlings are so diffrerent!
HTH