Here is what I usually advise.
The actual procedure is not painful; in fact the only thing you feel is a scratch when the anaesthetic goes in. The actual removal of fluid is just a feeling of pressure if done properly. I must stress if done properly; do not let anyone practice on you insist on someone who is experienced.
It’s after you MAY get something called ‘the headache from hell.’ To cut down the chances of getting this you should lay flat for at least 3 hours do not even get up to go to the loo; use a pan. Drink at least 2 litres of classic Coke, not diet; it’s the caffeine that aids replenishment of your CNS fluid. Being your drinking a lot take one of those bendy straws otherwise the bed will get more Coke than you. If you want a change of drink very strong coffee.
These things will drastically reduce your chances of getting a headache that could last about 8 days. If you have a couple of days off work and rest if you do not get the headache, if you do 10 days off work.
If the headache last more than 10 days you could need a blood patch; especially if there’s a wet patch on the bed in the area of the spine after a night’s sleep; this is rare.
So as you’re having more fluid taken out definitely lay flat; do not move for 3 hours after.