Applying planets orb

Hi My Mercury is at 3.10 aquarius,Júpiter at 12.20 conjunct MC.If I am to believe Porfiry, Mercury is applying to Júpiter.In his book he says a planet at 20 of a sign is separating from one at 10,so I guess the same applies to application from a fast to a slow planet. Any thoughts welcomed

update--actually he contradicts himself.Applying is 3 degrees orb only but in the following page he says a planet at 20 is applying to a planet at 25

The 3-degree orb is a different kind of thing. As long as the asepct perfects in the same sign, they can provide "testimony" for each other.