Heavy weight, allow the aircraft to accelerate normally towards 'S' speed which will possibly result in auto-flap retraction i.e. from 1+F to 1 (slats only). Approaching Green Dot, select flap 0 and MONITOR acceleration towards 230 compared to Slat retract speed.
If in doubt, PULL SPD at, say, 225-228 knots, when the slats are in, MANAGE SPD, no-overspeed. Job done.