It depends. For you, the unknown variables are what you need/want to finance, what conditions a bank loan has, and which KfW level you want to achieve.
The program Energieeffizient Sanieren is an option for the renovation:
It's all relative. For the grant, I only needed a few days - but settlement is only at the end. 0.75% for 10 years is not bad, but it's "only" 10 years.
The energy consultant cost €3,520 (construction supervision only online, I don't need him on site) - you get 50% back of that via KfW. Application is straightforward and fast.