I use rooting hormone to root cuttings. I see no problem using it for seedlings or even transplants.
Good luck with the GDP. I grew the original plants and a bunch of clones last year. You can check it out at GDP to start the new year
I use 1 gallon fabric transplanters for the intermediate pot. They have a Velcro enclosure . Its like peeling a banana when its time to transplant.
This is one of the GDP going into its 5 gallon final home
