Ahoy,
so I can only show how we approached it...
Boss: "Honey, do we want to build?"
Me: "Yeah, if you want"
That was just said like that at first, but day by day it turned into a fixed plan. In the first days we observed the real estate market (we still do that today). So we know where it might lead us.
Two weeks after our decision, we went to a financing service provider. There we already gave very concrete numbers, with all the concerns one can have (unemployment, illness, death, etc.)
After about 4 hours, our approximate budget was set... how much the house may/can cost, what energy efficiency the house should/can have (70 or 55 or 40), what the land may cost max, small installment and high special repayment, high installment and small special repayment, etc. etc. etc.
With this knowledge, we then went through various house construction companies. That took a lot of time. I think we visited 20 providers.
It quickly became clear to us that a bungalow was out of the question because they are simply more expensive than a 1.5-story house. So the type of house was decided pretty quickly. We visited both solid house and prefab house providers, although our choice was already fixed... it was to be a prefab house.
Gradually other things were added, such as a garage, maybe a pool, terrace. All things that you have to consider. Last but not least, and in my eyes absolutely indispensable, to keep a small financial cushion in mind. Never calculate and plan too tightly, rather add a bit on top, e.g. always round up various amounts instead of sugarcoating it. Such things can cause nasty surprises.
Best regards,
SaRo