Event recurrence number as variable in event description Google App Script Calendar

I have the following code that creates an appointment that recurs 6 times. This is working nicely, however, it would be great if I could access the number of the recurrence in a variable and print that in the title as "appointment 1", "appointment 2", etc. Is this possible with the addWeeklyRule method or would it only be possible with a loop?

    var eventSeries = cal3.createEventSeries(name, startTime, endTime, CalendarApp.newRecurrence().addWeeklyRule().times(6), {
    description: descriptionText

Found a way to do it without a method but just got the events and changed the title. Had to add a wait step though because it couldn't find the events right after creating them.

Utilities.sleep(5000);

var untilPlanned = new Date(startTime.getTime() + (1000 * 60 * 60 * 24 * 7 * 8));
var startPlanned = new Date(startTime.getTime() - (1000 * 60 * 60 * 12));
//search for events 
var eventsPlanned = cal3.getEvents(startPlanned, untilPlanned, {
    search: descriptionText
});
for (var k = 0; k < eventsPlanned.length; k++) {
    var sessionNo = k + 1;
    var title = Sessie: " + sessionNo + "
    eventsPlanned[k].setTitle(title);
}