Ive been taught to let go of starter button at 50%, if needed wind on a bit for FLI to come up, then do hyd checks etc, switch off prime pump and then when ready wind up to flight setting and governor does the rest.
Prime pumps are switched off as the 120 has siphon suction once started and doesnt need pump to self sustain. Manual says to switch on prime pumps in flight if you get a low fuel pressure caption. When I was at the factory I was told that this was so that if you had a crash fuel would not continue to be pumped if electrics were still on. May well be something to do with the crash resistant fuel system/tanks in the EC120. I believe the EC130 is the same which also has crash resistant fuel system as standard.