My son will be 3yrs 3 months when this baby is born... I have no idea what that really means, but I'm very happy that my son is a bit more settled & independent now as I found the baby & early toddler phase very tough as he doesn't sleep much. Also he'll get free Nursery time, so I will get some 1on1 time with new baby without it costing us anything...
My brother & I were only 22 months apart and fought like cat and dog until we were in our THIRTIES.... so I know being closer together is no guarantee of getting along - it's more about personalities, but as my son is very verbal I'm hoping I can explain a bit more than if he were younger and hope to navigate any jealousy that way.