Acquisition of builder: special termination right for building insurance?

Hello,
we received our middle house (new build) from the developer on 31.08.18.
I sent a cancellation to the building insurance yesterday.
I have a question. When is the earliest one would be out of the insurance?
Is there a waiting period with a new building insurance? Should I have preferred to cancel with a desired date?

Don't understand the question. Just ask the insurance. A new one can be arranged quickly.

This is the insurance of the developer. We are not allowed to provide any information. And I cannot reach the developer. It takes too long for me.

If the insurance is from the developer, and you don't get any information, you legally can't cancel it, right?! Or did you pay for it? Then you will also get information...

Whoever owns a house must insure it. Whoever sells it transfers the insurance to the buyer, who then has a four-week right of cancellation; otherwise, the insurance remains theirs. This applies from the transfer of possession, but I'm not entirely sure—it can also be from the transfer of ownership. The old insurance is always valid until the end of the year, so on 1.1.19 the OP thus needs something new, or else he takes over. It could have been a cheap policy. Karsten

How quickly will one be terminated? I hope not too quickly, as there is a waiting period for the new ones. Is one termination notice enough or do we have to provide proof of the transfer?