I wouldn't hold your breath on that , nor raise your expectations of a repetition, nor if it did happen, that you and you alone, would be able to take advantage of it.

The Kingdoms map shows quite a number of kingdoms with two or three thousand towns rather than thirty to sixty thousand.  None of the recently created kingdoms have that number so I suspect that the number of towns reflects differences in migration rather than your mythical glitch.  But if you want to keep the faith about a glitch, and if you are a patient person, you could look from time to time at the newly created kingdoms on the Kingdoms map looking for one with two to three thousand towns.

The question is funny because you're asking about the timing when a glitch will recur. But any kind of errors have the characteristic that they occur unplanned and also unintentionally.

But since I didn't know the facts, I looked on the map for older kingdoms with only 2-3k cities. Indeed there are, and when you look at the kingdom, it looks like it was never settled normally. There aren't the thousands of usual abandoned mini-towns everywhere.

If you want to take over such a kingdom it doesn't seem to be a fundamental problem, go and try if you have the fighting strength. It would also be of no particular advantage if such a kingdom were to arise accidentally  again, because very strong clans from outside would also try to take over the supremacy there again and again. 

Besides, I believe that the impact of the abandoned mini-towns is grossly overestimated. According to my own samples, these cities below level 10 have an estimated average influence of less than 20k. Assuming 90% of the cities in a kingdom belong to it, it affects about 40k cities in an average kingdom. So the total influence of these cities is 40k x 20k = 800M. This corresponds to the influence of a single active small town of about level 24. Thus the influence of this "spawn" can have no effect in any drawings of the kingdom.   

Unless it was a real 'glitch', I think what you may be speaking of, might be the occasion when someone appeared to have managed to hack into the program, and get it to churn out many kingdoms, with many non real players in them.