No defined procedures.(always takes a while to get your head around it!)
But common sense says if you believe the flight paths will cross then apply the appropriate wake turbulence separation timings.
With reference to your example, more caution would be needed if one runway had a displaced threshold etc.... there would be more chance of the flight paths crossing! Also aircraft types would be important.... yes a helicopter might get airborne before the point of touchdown of the heavy... but how can you ensure he will not fly through the approach profile (and hence wake!) of the heavy lander......
Again.... common sense needs to be applied. If in doubt - apply the separation.