I have had lumbar puncture (LP) about 2 years ago. They did it in the morning and outpatient procedure. Procedure was done by a Neurologist in a hospital.

Procedure itself is simple (technically) and takes only few mins. They made me to lay down under a table and I think mine was guided through some machine (?). Neurologist came and numbed the area and I felt some pressure and all done in few mins. Since my Neurologist at that time ordered all the tests for the spinal fluid (including Lymes) they took 4 tubes of fluid.

Neurologist even asked me can I guess what color the fluid is? I said no color (if everything is fine)

One of the main concern for them is Intracranial Pressure (ICP) which they measure using an instrument once they inject needle and take it out (opening and closing)

Since everyone warned about Spinal Headache for few days I made sure I didn't get up for about 4 hours (though they said 2 hours is enough). You should not drive after the procedure and go home and lie down for the next few days. Luckily I didn't get Spinal Headache (besided my usual dull headache) and if Headache gets brutal they can do a blood patch which I hope you didn't have to do and the hole heals by itself.

Since I have smell disorder everything smelt awful for few days which I thought bizzare!

So that was my experience and not a bad one

Cheers!