Smartphone price development after release of the successor?

When does the price of an older model drop when the new one has been released?

To be precise, when and how strong will the Huawei Mate 20 Pro price reduction be when the P30 and P30 Pro appear?

The price drops long before the new model is even in sight.

With the announcement of a successor, prices are falling.

Yes, but I mean that, for example One week after the release it will be 100 euro

I'm talking about BEFORE the release.

You should not chuck at Mediamark but on Ebay and on the internet.