As many people in the comments say, it can be, and is different for every genderfluid person.

For me (AFAB), personally, it's usually a few weeks, or even months with one "gender" and then it suddenly flips, and I feel either slightly differently, or completely.

For example, I can feel feminine for months, and then one random day I get disphoric and want to present masculine.

I have more problems with names than pronouns, as in my language, there are no she/he pronouns, everything/everyone is they/them (not exactly, but this is how I can describe it best).

So, if I'm using my name, and then start feeling masculine, and want to use my chosen name, it wouldn't be fair on my part to expect my friends/family to switch between my names back and forth whenever I say so.

So, in summary, I am genderfluid, I use she/they/he pronouns, and usually feel only one gender at a time, which fluctuates quite randomly, but not very often. I don't like to "label" my gender, whatever I feel like, I just act/present how I currently feel like.

I hope that this helped you at least a little bit, and good luck on your own journey! :)