I want mass drops every 10 minutes and i just cant figure out how? could someone please help. thanks

I can tell you that would not be adviced to do every 10 minutes?? It takes a few minutes as is just for the planes to spawn in and make it to their drop points as is, so if you did do this every 10 minutes it would in a sense be running constantly

how to set the time for mass and which time do you suggest?

MagNifAkle

how to set the time for mass and which time do you suggest?

See the documentation it is all in there.