You’ll need to think about how much of that 1Gb you want to use. Are you happy with it peaking at 1Gb/s and maybe stopping other things working?
The network usage of nodes is going up and up at the moment. So it’s even more difficult to say at the moment. At the start of the week I’d have said 20 nodes will use about 0.75Mb/s down and 0.5Mb/s up on average. Now it’s more like 3Mb/s down and 1Mb/s up.
The other aspect is the number of connections or sessions on your router. Nodes use less of them than they used to but it’s still a consideration. 20 nodes just now use between about 200 and 1,000. For normal ISP supplied routers and other cheap ones you want to limit it to just a few thousand. I’ve seen routers fall over at 5,000 sessions.
There was much discussion of these aspects here - Routers for advanced setups
Some of it is out of date in terms of the state of the network then but things about routers and connections are still valid.
Nodes are now having to store about 4GB now of the 32GB allowed rather than hardly anything before when the network was larger and it’s going up so that is more of a consideration than it was previously.
I would say start with 100 but build up to that over a couple of days because of the burst of traffic when they start. Then see how it goes because nodes are getting busier all the time at the moment.