Contract with prefabricated house manufacturer - insist on delivery time?

Even if the wording is invalid, there is still no deadline stated, so what applies then? As far as I know, companies are not (of their own accord) obligated to include deadlines; the client must pay attention to that. If no deadline is mentioned, they can indeed keep you waiting longer—holiday season, Christmas season, weather, etc. And you have no choice but to wait.

Always stay calm! I have never heard anywhere that the house project was started on time. That is just part of it. However, be careful not to be strung along.

Basically, I am satisfied and really don’t feel like arguing. I’m just thinking about the best way to proceed if the delaying of the delivery date continues. I definitely don’t want to risk missing the deadline of the fixed price guarantee

So you’re concerned about the fixed price? Then express your concerns and they should confirm it.