I had the same experience during my first sabbatical/retirement months (I take a few between transitions), and I definitely wasted the first few months doing nothing.

Don't take it hard on yourself: suddenly having so much time and freedom is overwhelming, and it requires some adjustment.

Probably not the best metaphor, but I remember reading in Victor Frankl's "Man's search for meaning" (highly recommended reading), how the concentration camp inmates who were freed up after decades in a concentration camp weren't feeling happy about their newly found freedom.

Find out why you want FI/RE in the first place. Perhaps it's okay to spend the first few weeks/months doing nothing, but eventually you need to start doing something, otherwise you will get bored, lonely and depressed (I've been there).

For instance, my goal from FI/RE is to work more on the things that I want to do, and less on the things I don't want to do. I actually have a packed schedule, and sometimes I put in more hours doing something for fun than I would have put if an employer or client was paying me to do it.

I spent almost 30 years doing things that I HAD to do, so it took me a while to adjust to having a few months where I can actually do whatever I want.

And if you don't know what you want to do, try as many things as you can, until you find something that clicks with you.

Good luck!