• it does not weaken you, only for the first half an hour, but at that time you are eating and resting
• your body makes the new blood in about 3 to 4 months, that is the reason you can donate only 3 to 4 times a year
• it will not affect your performance
• If you are healthy (and you are) you can do anything after donating that you did before. They suggest you do not smoke afterwards and do not donate if you are on your period. I donated when I was on my period and a cigarette is the first thing I have as soon as I leave the hospital :) I was always fine. Since I presume you do not smoke and definitely do not have periods, you will be fine :)
• You can donate whenever you want, in Zagreb, donations apartment in Savska 3 is open from 8 to 20 every day, on Sundays a bit shorter. Those organized donations are a way of promoting and making more people to donate. You can really donate any day you want

If you have any more questions, I will be happy to answer them. I am so glad you are interested in donating. Thank you!!! 💚