well what i usually do is i take peat moss and just calculate in my mind whats enough, then i take some perlite and then throw it in, and mix it around, making sure i see perlite, if i see little, its too little, if theres alot, then i add more peat moss, i do it all by hand, no cups or anything, to me if i do it with cups i think something is wrong, when i do by hand it is so much easier for me to caluculate how much to do, and i wear plastic gloves, just incase, hehe, the tight plastic doctor gloves
maybe this works for others,
so all in all, what you said is fine
as long as you see perlite its fine, if you see too little, add some more