I was prescribed not just cyclizine and prochlorperazine but also metaclopramide. I think the doctor at the hospital went a bit overboard because they didn't want me back for another visit!
I have primarily taken cyclizine twice a day, and use prochlorperazine and metaclopramide as 'top-ups' if the nausea creeps in again.
My schedule is normally something like this:
6-8am: Take cyclizine as soon as I wake up
12pm: Take metaclopramide if still feeling sick before lunch.
4pm: Take cyclizine again (if needed)
6pm: Take prochlorperazine if still feeling sick at dinner time
It's just my little schedule that I've found works for me, and usually keeps the sickness away (only vomited once since I started these meds 8 weeks ago).
Each medication has different side effects but I generally find that prochlorperazine is the worst for drowsiness - hence why I take it in the evening and not in the middle of the day. Cyclizine causes drowsiness too however I seem to have got used to it now and don't zone out as much as I used to. Metaclopramide doesn't make you drowsy but does make you need the loo as it works by keeping your stomach emptier.
One thing I will say is don't put pressure on yourself to cut them down if you reach the 12 week mark and you are still nauseous or vomiting. I am at 18 weeks now and still nauseous - although nowhere near as much as I was at 10 weeks. These medicines are safe to use in pregnancy and if they give you a better quality of life then they are worth taking.
Sorry quite a long reply but I hope it answers some questions!