When to start implement network functionality?

Hello!
I’m one of the programmers in a group that is working on what’s going to be a multiplayer, both local and online, party platformer game. I’m designated to work on the network functionality and I have a few questions regarding how to structure the project. We are currently two programmers in total.

The way I see it there are 3 ways to go about it. Either we build both the local and online scenes parallel to each other, build the local multiplayer scene first and then “port” it to a online multiplayer version or we build the online version first and then the local version.

How should we go about it?
I can see some strengths and weaknesses in all three but what do you think would be the most efficient?

Or is there another way to do it that I haven’t thought about?

I’m a bit confused here, what do you mean by the local and online scene?? you mean the same game can be played both online and offline? if that’s the case then I suggest you build the online version first, and offline would be a self hosted so it just runs a local server.

Right sorry.
The way I think is that we have one scene dedicated for the online play. It would hold, or use, all the network code but only support one controller from each client. Then through network code it would connect all online players.

The local, offline, scene would not have any network code but instead be constructed around the ability to connect multiple controllers.

Both scenes will have the same gameplay besides the notwork and controller part.