Be sure to neutralize the Ospho before applying anything over it. If not it leaves a film that will cause adhesion problems.
I made this mistake once and it cost me a complete redo of the roof on my signature car.
Once you have the rust converted, apply another coat of Ospho and then before it tries wash it off with soap and water using a Maroon Scotchbrite pad. Rinse well and blow dry with an air hose. Wipe it down with 710 Wax and Grease remover and let flash completely.
What do you mean "flash completely"? Flash rust?
Well Jim I know you said don’t wait a month but I had to lol. No signs of flash rust on any part/s the frame has been bare for 3-4 months and not a spot of flash rust anywhere. Still plan on doing some touch up blasting and cleaning with 700 WGthat is flash rust on the axle. no need to worry about that. you can epoxy right over it. just do it soon. dont wait a month from now.