Can you explain your use case more? Are you using Recursive Blueprints to automatically add trains or are you doing it manually?
anyway to make them wait a few seconds to get all their fuel loaded?
Yes. If you are using RB then the circuit that triggers train spawning could also make a rail signal be red for a few seconds to prevent the train from leaving.
Or if you are automatically inserting fuel with inserters then you can have 12 stack inserters inserting fuel at the same time, filling the train with 144 coal/150max instantly so you don't have to delay the train at all.
I had assumed you would have the refuel station as the first station. Also I tested the mod with nuclear fuel so I forgot about any problems just having a tiny bit of fuel would give you q:
If you are manually inserting coal then you would never insert just 1 coal into a train that's in automatic mode anyways?
Maybe if you have bots fill the train with coal and you are placing the blueprint manually this could be a problem? Or did I miss any scenario? Please tell me more!
Glad you are enjoying it! :D