[canana]

Just to add to the above suggestions...

I'd also make sure you introduce them to each other outside of your home, on some neutral grounds, like a park or something. And make sure both are leashed and both on the ground (i.e. don't introduce the puppy while you're holding him). If they're okay, take them for a walk. Maybe have two humans, each with one dog.

Once you're home, all the humans walk into the home first and let the two dogs walk in after you.

I think your idea of giving them a slow transition to each other is great. I also kept them separated when I brought home baby Casie.

It's very likely that the first dog will not be happy with the new puppy. There may be some initial jealousy issues, but that will eventually subside, as long as you treat your first dog the same way and always give him more attention.

Then, eventually take them for daily walks together. Train them together. And then separate them when you're away from home.

From my own experience, Scottie took weeks before he was comfortable with Casie being around. He was pretty jealous the first day and refused to even let me touch him! I went through thoughts about whether it was a bad idea to get a second dog, but eventually with consistent training and walks together, they started bonding, and now, they have a routine playtime every night before going to bed.