I think have at least 2 years between each dog, that way each dog has the time to mature before you introduce another.. I have 4 and Ill be honest the more dogs you have the harder it is to get the individual training in.. something will slide.. so wait a while
Ive seen folk with 4-5 dogs all under 4 or 5 and its obvious some dogs just arent getting the one to one they need. and believe it or not some dogs do better as only dogs.. you can always come on col meets to meet more spaniels and its good to have dog walking buddies where you can go somewhere safe and let them off lead to rollock around and play.
also Ive no idea of your circumstances but 2 dogs is twice the expense and with the credit crunch and everything its something to take into consideration.. Im 50 my kids have flown the nest.. Im lucky enough in that I can please myself.. if I was early 20s thinking of starting a family then Id say stick to one dog as when new human kids come along circumstances can change ie more expense , constraints on your time etc..
enjoy the dog you have and wait a wee while..