What can I realistically afford as a rate?

and on parental leave? then it's under 3k, right? or not?

so we can skip the baby discussion. of course you can spend 8,10,15 k on the baby. I will stay in the range of 1-2 k.

Here I naturally agree with you - it really has nothing to do with your original post.
But on one point I have to come back to it:
If your first child arrives during the savings phase, then:
- Your savings will at least partially decrease again (by the way, the mindset here is real: better to buy something for the child than to save it)
- Your savings rate will drop significantly
and - this will be the most serious
- Your wife will likely not be able to work full-time anymore (after the parental leave) - unless you have caring grandparents who can always and anytime take over the child.
3rd problem we currently have:
Grandparents on both sides live about 600 km away. The rest of the family also does not live very close. My wife has tried 3 times in the last 1.5 years to re-enter the working world. 2 times part-time despite full-day childcare failed (because the working hours in retail hardly match the daycare hours and the constant strain for us as well as the kids became almost unbearable). Now - from today - a new attempt on a 450 euro basis <-- in the meantime we lost the full-day daycare spot and despite "only" a 450 euro basis job we don’t know how to cover the times (today’s gross earnings almost completely go to the babysitter - of course here net).
The next 4 weeks are (more or less) covered - after that (when the babysitters return to school) - no idea.
Retail - comparable to hairdresser

Even with parental leave, it is more than 3 k. I earn about 2900 net in 2 years at tax class 3. Plus her parental allowance. Although we are currently in the planning phase. That means hopefully there will be a child next year. After one, she will definitely go back to work. And that is also possible without any problems in her current job. She is the key figure and branch manager there. The boss supports her in everything.

We are lucky that our grandparents on both sides live only 10 minutes away.

You are classic "spin doctors"

Well, that's lead time, I hope not.

The fact is in 2 years: Minimum: My net 2900 € + parental allowance + child benefit. That is the absolute minimum.

Optimistic if the child is already here and she is working again:

Maximum: My net 2900 € + her 40/30 hours per week + tips + child benefit. That is the other variant. There is nothing in between.

The income may be sufficient if one does not live too extravagantly, but in one thing I must agree with the previous speakers: The equity is not impressive and will not increase much due to the wedding and initial purchases for the child.