Here is my response from the KfW, it reads reassuring at first:
“Dear Mr. Egbert,
Thank you for your inquiry. Please excuse us for only responding today.
We assume that the funds provided by the federal government are sufficient. A product launch always means increased demand. This is also true for the Baukindergeld.
In 2018, there was the special circumstance that applications could also be submitted retroactively from 01.01.2018. In 2019, we expect fewer applications than at the product launch. It applies: We are happy to accept applications as long as funds are available.
The total volume for funding with the Baukindergeld amounts to nearly 10 billion euros.
You can submit an application for Baukindergeld until 31.12.2023 at the latest if you purchased your residential property or received the building permit between 01.01.2018 and 31.12.2020. The decisive date for the purchase is the signing of the notarized purchase contract.
It is important that you submit the application within the first three months after moving in. The move-in date is stated on your registration confirmation.
Once you have submitted your application, the Baukindergeld is reserved for you until our final review.
Kind regards
KfW”