Auto fill cells with custom script - enforce sleep between calls

I have a custom script which calculates the distance between two addresses. The script uses API call to Google Maps. I have my addresses listed in one column (about 4000 addresses), the other address is fixed. If I abuse the api calls and fill down all the 4000 cells, the api locks for 24 hours. Is there a way to enforce a sleep call between the subsequent cell fills? I got the script from the web, here it is:

/**
* Get Distance between 2 different addresses.
* @param start_address Address as string Ex. "300 N LaSalles St, Chicago, IL"
* @param end_address Address as string Ex. "900 N LaSalles St, Chicago, IL"
* @param return_type Return type as string Ex. "miles" or "kilometers" or "minutes" or "hours"
* @customfunction
*/   
function GOOGLEMAPS(start_address,end_address,return_type) {
    // https://www.chicagocomputerclasses.com/   // Nov 2017   // improvements needed
     var mapObj = Maps.newDirectionFinder();   mapObj.setOrigin(start_address);   mapObj.setDestination(end_address); var directions = mapObj.getDirections();
     var getTheLeg = directions["routes"][0]["legs"][0];
     var meters = getTheLeg["distance"]["value"];
     switch(return_type){
    case "miles":
      return meters * 0.000621371;
      break;
    case "minutes":
        // get duration in seconds
        var duration = getTheLeg["duration"]["value"];
        //convert to minutes and return
        return duration / 60;
      break;
    case "hours":
        // get duration in seconds
        var duration = getTheLeg["duration"]["value"];
        //convert to hours and return
        return duration / 60 / 60;
      break;      
    case "kilometers":
      return meters / 1000;
      break;
    default:
      return "Error: Wrong Unit Type";    }    }