Go to Walmart and buy that $20 super annoying crying baby doll and carry it around the house. The dogs may be ubber interested but better to get them accustomed to it now rather the later. Put crying/giggle baby in the swing, the high chair etc.
Set the swing in motion this alone can scare them. Get them used to that motion as they may want to smell it etc and it will bonk them and bang them and the swing will stop etc.
Go for silly walks with the dogs and stroller. Often dogs are scared of the stroller so to get them used to walking beside/with it before you are juggling baby too.