I believe in your case I would also prefer to wait a little longer and see what salary your girlfriend can negotiate. It's not that much time anyway, and during that time you can calmly plan everything, get everything transferred, clarify what is allowed to be built, etc. But for financing, you are clearly better off with two salaries, and by then you will also have more equity. There is actually nothing at all to rush now, since you already have the plot of land secured. The BA thesis is not rocket science (yes, I wrote mine with a 4-month-old child, so I know what I'm talking about), so she should focus on finishing her studies and simultaneously already apply with the current grades. However, the topic of childcare is important here: How secure is the daycare spot for you? Everything depends on that for you in the end, because otherwise one of you won't be able to go to work.