Yep that's the same as me.
Ok so timing was a tough nut to crack for me. I've always been quite bad at that part, so for this exam I remember practising past papers as often as I could, so I could get used to the time constraints. This might not be a problem for you, but I also take English, where you have two and a half hours to write about the same equivalent as the classics papers so it gets quite difficult. So past papers past papers past papers. One of the most crucial things is to know the exam. Look up past papers, even if you don't have a go at all of them it's still helpful to read the questions and see the format. Also look at the mark schemes, find out exactly what the examiner is looking for.
Now I'll explain how long I took for each question, but different people work at different speeds so you have to take that into account. Just spend however much time feels right for you. In the Cicero exam you have your 5 mark question, 10 mark question, 20 mark question and 30 mark question right? With the 5 mark, it should take you about five minutes, since it's just general knowledge of the unit (eg what year was Cicero praetor) Sometimes you'll get an extract which might take you a little bit longer, and remember to read it carefully if that's the case. So after that you have 1h25m left. Next is the 10 mark question, I spent about 15 minutes on this one because again it's fairly basic; you have to make 10 points. So now you've got 1h10m left. Plenty for the 20 mark and 30 mark questions. I spent 20 minutes on the 20 mark question in the exam. It doesn't sound like a lot of time, but if you know what you want to talk about and have enough knowledge to back it up, then it's enough time. That left me a good 50 minutes for the big one. I gave myself 5 minutes planning (because planning is so important for an essay question and you might even get marks for it) and then I wrote for 45 minutes, until they told me to put down my pen.
Hope that helped a little
As for techniques, I remember the night before the exam being full to burst with Cicero knowledge. I just revised as much as I could. Talking to people about it helps. If you explain the things you've learnt to family/friends who won't get bored of it, it really gives you a confidence boost, and helps you to memorise it all. Confidence is so important.
Just memorise all the knowledge you can, practice writing past papers under timed conditions, record yourself reciting dates, use different medias to keep your revision fresh (documentaries, dramatisations etc), make flash cards, read your notes and write them out repeatedly till they stick, keep calm, get lots of sleep and don't worry.
I know your exam is only on Wednesday but that still means you have this evening and tomorrow and the day after to revise as much as you can; it's not too late. You'll be fine.