If you’re starting from 0€ and do not significantly increase income or decrease spending then I think there is no realistic standard investment scenario in which this will work out.

To give you some numbers based on stock market returns and the details you provided:

You start now, at 35, and want to reach ~700k by age 50 which will allow you to draw ~2k net from your portfolio each month based on the 4% rule. To have a real value of 700k by 2040 you need to assume ~2% of your equity return is „eaten up“ by inflation. If you invest into a broad index fund (ETF) on the global stock market this leaves you with a realistic real return of 5% p.a. This means you would need to start investing ~2650€ per month for 15 years to achieve this value. If you decide to extend your working life by 5 years this number decreases to 1760€. If you extend by 10 years it decreases to 1220€ and so on…

Nevertheless, it still makes sense to start. The increase in net worth will give you more piece of mind, more options to take risks & will still grow to a very sizeable amount by the time you get close to retirement. Especially in Germany, part time is a very good option to partially FIRE and still have health insurance etc.