Separating "baby" swords

[bwilly36]

OK, I suppose that this is going to sound like a very sophomoric question, but I have two brazilian swords that seem to be doing well and have several arms with the "baby" plants growing at several joints of each with 2-3" roots growing from each. At what point do I separate this plantlets from the parent and place them in the substrate?

Thanks for the input,

Bob