Yes that is okay. All the chapters of biology are somehow related with each other and as you progress in this journey, you will be able to find all those relations and things will go on getting clearer in your mind and your knowledge will keep on increasing with concepts cleared in your brain. So to begin with, it is okay to start with body fluid and circulation and then the other chapters for human physiology.

Refer to the website below to know more about the same (biology preparation tips) -

https://medicine.careers360.com/articles/how-prepare-for-neet-biology

Best wishes. Thank you.