How many papers should I take in next ACCA exam sitting?

First of all congratulations on starting ACCA professional qualification and I wish you great luck.

Coming to your question, then your question can be answered in one idiom: Don’t bite off more than you can chew!

So, considering your daily routine and your daily activities you should decide that whether it is doable for you or not. And believe me no one can tell you exactly what is doable for you and whats not as nobody knows YOU better then YOU.

However, here are few tips which might be of some help to you:

If you are a FULL time student i.e. not doing any kind of job and also have no specific engagement on daily basis then it will be really good that you invest all your time in studies and take up 4 exams in one sitting and thus getting the maximum benefit out of this option.

If you are PART time student i.e. doing some sort of job either full-time job or part-time job then you will have to sit down and think how much time exactly you can spare for your studies. I will be writing detailed articles about preparing different subjects and tactics you should follow under different circumstances soon. But for the time being here is a general breakdown of the timings you should spare for each subject that are relevant to you:

ACCA F1 – Purely theoretical subject and actually talks about how organizations work and basic stuff related to managing organization’s people and system.
So you should spare 4 hours a week for reading and practicing this subject.

ACCA F2 – Demanding subject and involves many of such topics which are new even to those who are familiar to accountancy area in one way or another. Needs lot of practice and also dedication to go through theoretical portion of the syllabus as it is of equal importance if compared to computational area of the syllabus.
For this subject I suggest that you should spare 10-14 hours a week to read and practice.

ACCA F3 – Includes basic knowledge regarding financial accounting but does involve many of the important topics related to financial accounting. In this subject though students have more computational related topics but still involve some theory.
My recommendation for this subject is that you should save 7-10 hours a week for this subject to practice and learn everything important.

Please note that my recommendations /suggestions are just to give you an idea about how you should approach these subjects this not the ultimate way to prepare for your exams. If you have more time to spare then its good as you will have more time to learn but if you have lesser time to spare then you should skip or drop few subjects or prioritize the topics you learn and your non-study activities.