Ok, with over 1300-1400hrs in IO520s, here's what I say:
First start of the day:
Mixture, Prop, Throttle, Full Forward
Lo Pressure Boostbump on until the fuel stabilizes, (usually a few seconds) then off.
Throttle to idle, or just a little bit off the stop.
Key the starter, it'll fire right up.
A hot start
Mixture, prop, throttle full forward.
Boost pump on then immediately off (like as fast as you can flick the switch)
Throttle to idle
Turn the key, it should start in a couple of blades.
Some of them (depending on how they're rigged) don't like the application of any boost pump on hot starts, but for the most part, that should work just fine.