I picked them up from David Frawley’s book ‘‘Mantra Yoga and Primal Sound’’.Of course it says that planetary mantras are best to use in the appropriate day and hour of the ruling planet.
I invoked Jupiter before a call to Nitika thinking that it will give a boost of success in the ritual.The mantra worked(at least i felt the usual shift)but i doubt about the success of the Nitika chant and i think it was Monday or Tuesday.
Imo it’s best to use them the correct way.I do a lot of silly things
If you want to get the most out of working with mantras and the planets your gonna wana dig into bedic astrlogy. There are actually methods to figure out what planets want to work with you and which mantras would be of the most benifit. You may get some decent general results but if ya want to be pinpoint accurate benifits with it ya need your chart looks at by someone skilled in astrology and mantra.