When the runtime starts your flows, it first looks for all configuration nodes and starts them. It tries to identify any dependencies between the config nodes and will start them in the right order to satisfy those dependencies. It then starts the regular flow nodes, one tab at a time, in the order they were added to the tab.
If you have a node that other nodes depend on, I would assume its a config node - as regular flow nodes don't, in general, have dependencies on each other like that.
If your node is a config node, and other nodes declare a dependency on it, then it will get started first.
