The best i ever did was 3 days... back in the days of my first 2-3 girls.. Actually i do "masterbate" but not cum.
I am a fan of CIM/COF so i tough the more i wank it before without cumming, the bigger the load is gonna be right? Bah... i realize later it dosen't matter much actually. Sure if you wank an hour before seeing an SP and cum, the load will be smaller, but just holding yourself 1 day before it is plenty enought.
I had a meeting last summer where i came twice with the first girl(last time i did) and had Kelly Summer planed(for the first time) 1 hour after. I still managed to buy a decent load even if i came 2 time, cause i wa extremely exited.
Second time i saw her, i saw Kate before, an hour before, came once, and i still managed to give Kelly a huge facial(i was aiming for mouth but it splashed everywhere) cause i was extremely exite(Kate and Kelly are really freaking hot and above my top) so that proved that holding it too much dosen't really matter.