When you add more nodes to your proxmox, the starting VM will be the number that you want to start from.
For example, if you have a 10 nodes at 301, 302, 303, 304, 305, 306, 307, 308, 309, 310 and want to add one more, then your starting number will be 311.
Your starting loop will be 11 (as that is the number in front of the subdomain).