It honestly depends on what you’re trying to do. For starting off, I recommend Brackeys “How to program in C# – Beginner Course”. Understanding the basics of programming, especially with a language like C#, will help you tenfold when learning in Unity.
If you’re antsy to get started with developing a game, check out the “How to make a Video Game” playlist. Using blender is not a necessity, since Unity’s asset store is full of free content so I recommend holding off on learning that until you’ve gained some experience with programming. This is all purely my opinion based on what i’ve experienced.
Let me know if you have other questions. Hope that helped some.