Duration until the issuance of the building permit in BW

Where are you building? We are in the Böblingen area and have been waiting for 4 months now. No approval yet.

In Stuttgart-Vaihingen

5 months in Heidelberg...

The question is actually also whether you mean a proper building permit or a "building permit" under the exemption procedure where you do not deviate from the development plan. With the exemption, you can expect a few days, which also cost nothing (0-100€) as opposed to proper approval procedures costing around 1,500€ externally.

In Stuagard everything runs smoothly. There Nexa is released. Without approval, no Nexa runs at all! ;-)

I would also reckon about 5-6 months... but no one can tell you exactly.

In BW it is regulated by law. State Building Code §54 para.5. The building authority must decide within 2 months. The exceptions are also defined in the State Building Code.
With us, the district office sent a link and access to a portal where you could check the processing status yourself.
Last summer we submitted a building preliminary request according to §34, meaning there is no valid development plan for our property and therefore everything had to be decided on a case-by-case basis. After two months no decision had been made yet. A polite inquiry by email was followed by an immediate response that some employees had been temporarily transferred to the health department due to Corona and that it was taking longer than usual, but they were making efforts to process our application as quickly as possible. Two weeks later the positive decision was there. We cannot complain, they were transparent and communicated well! Enzkreis.

In BW it is regulated by law. State Building Code §54 para.5. The building authority must decide within 2 months. The exceptions are also defined in the State Building Code.

Yes, I had that hope when submitting our building application as well. We have now been waiting for exactly 5 months (!) for our building permit in the simplified procedure (BaWü). As soon as we have the permit, I can report on the details. We have always followed up, asked politely, responded immediately to inquiries, etc. But what can you do in the end? Complain to the superiors? That would also reduce the chance of getting a building permit. Keep your fingers crossed and wait.