Hello,

This type of cutting should be allowed to form a dry callus over the cut, then placed in soil.  Typically this takes 1-2 weeks, but depends temperature and humidity.  Make sure to keep evenly moist but not soggy while the plant creates roots. Here is additional information on growing Epiphyllum.

https://extension.oregonstate.edu/gardening/flowers-shrubs-trees/orchid-cactus-epiphyllums 

I hope this is helpful. Thank you for contacting Ask Extension.

Ruth