Set number of instances to draw with instanced static mesh?

Is there a way to draw only a subset of the instances of an instanced static mesh? Like, if the total Num() of transforms is 1000, could you tell it to only draw the first 500?

I’d like to have a very large number of instances, and be able to slowly increase the number drawn.

So, is this not possible? Is the only way to change the number of instances drawn in an UInstancedStaticMeshComponent to add / remove them?