Preventing rust becore paint

Well I went and bought kleen strip concrete and metal prep and diluted it 3 to 1. There's a bunch of tiny rust spots on the car so I sprayed and brushed all the bare metal. The kleen strip is the same thing as ospho just stronger and was only 18$ a gallon. I don't want to spray the epoxy yet as I don't want to have to scuff it before paint and the car is only 2/3 stripped down.