hi there, as sperm have take approx 3 months to develop and mature then it takes 3 months for vits etc to have an effect. I think they say that no ejeculation for the 2 days before will ensure a bit of a 'build up' if you know what i mean.
I'm sure vitamins etc have a positive effect (we used the zita west ones for men) but you'll have to take them consistently for at least 3 months. good luck!
My DH had a PESA on July 7th at the ARGC, we had not done any preparation, other than a healthy (ish) diet, but no vits. The procedure was carried out under sedation, but my DH was in no pain, and to be honest he would only have needed the actual day of the procedure off, but he was on holiday from work so also took it easy the day after the op, but otherwise he was fine.
What I would suggest you finding out is how many vials do they get, how good was the sperm, and does your clinic do a trial thaw! to see if the sperm survive the freeezing and thawing, this is of course if you are freezing it. Good luck to you all with your treatment, hope it's succesful.