I want a Niagara emitter to warmup，but can not find the parameter.
A bit late, but here’s the answer -
Window → System Details
It took me a lot of time to locate it, hope someone will find this useful.
As far as I can tell, this is not an option anymore (at least in my installation of 4.26.2). So it’s unclear how to set a warmup time for a Niagara emitter again.
You can always set the warmup time in the system, which every emitter needs to be placed in the scene, but it’s still weird that you can’t even set a preview warmup time for an emitter (or that such an option is so hard to find).