This is a great question. It can be tricky to wait for all clones to be matched. There's not a perfect solution that I am aware of, however there is a strategy I use that seems to work well.

1. Wait for the parent to be created.
2. Call the GetClones method of the control and extract a proxy to get the count of the clones. Make sure the proxy is local in scope and record its value to a local variable.
3. Enter a ForLoop whose limit you'll adjust to suit your needs. The limit will essentially be how long you'll wait for.
4. Out of the ForLoop pause for a brief amount of time. I like to use either 250ms, 500ms, or 1000ms, as these are relatively round values. The higher the value, the more potential extra time you are adding to your process above what is absolutely necessary. If this is unattended, I would play it safe and go for a higher value since potentially an extra second per transaction will likely not affect anything. If it is for an attended process, you might consider going lower to provide a better user experience for the most part. Since matching generally occurs linearly (i.e. one control after another, especially within a single threaded process), you'll likely see matches come in regularly as they are matched on the page.
5. After the pause, call the GetClones method again and extract a proxy to get the count. Make sure this is local in scope as well. Compare this value to that of the first count and see if they are equal.
6. If they are, you may break your loop and continue.
7. If they are not equal, update the initial variable to your current count and allow the next iteration of the ForLoop to occur. The initial pause will happen again allowing more controls to match. This should change the count when you check it again allowing you to tell when it has reached equilibrium.
8. Adjust your limit based on the length of your pause. If you set your pause at 1000ms, then setting it a limit of 30 will effectively wait 30 seconds (very slightly more technically since the execution of each steps takes a few ms, but none of the operations actually take any appreciable time).
9. I also like to add one more check before I break where I pause and check once again. This is just being cautious and may not be needed in your application.

The idea here is that your pause must allow time for the clones to match. It won't work if you have a situation with a dynamic page where controls are added at random as in that case there technically is no "done" for the clones.

In short; loop until you get the same count of clones consecutively.