I’m a sophomore right now. In our school, it’s usually not allowed for students to take an AP class until junior year. I’ve taken all the available honors classes. I plan on taking 4 AP classes next year. Would the jump be too much?
Hmm I took 3 APs sophomore year after not taking any freshmen and I felt very stressed, but this was more due to my depression and somewhat perfectionist attitude?
(If you’re curious, I took Calc AB, Euro, and Psych and got 5s, so you’ll probably have enough time to prep for the tests if you take 3 or less, but 4 should be reasonable.)
To be honest, now 3 APs seems very easy (I’m taking 6 now). I’m more easy going on myself and don’t stress about every less than perfect grade during the 1st quarter (grades aren’t as hard to go up as you think) now that I’ve learned from sophomore year.
There’s also no harm in registering to take all 4 classes and transferring out if you feel like you’re struggling (before 1st interim passes grades still don’t count, at least at my school). I think that the 1st months of APs are the hardest because you’re not used to the workload, but it becomes manageable with time. If you are a hard worker but don’t overdo it, you will be just fine 
To answer your question there are a few factors they can play into your decision. First, are these classes “hard” in your school, where a factor(like a terrible teacher) causes most students to not perform well/do more work then needed, ask upperclassmen students to get a feel of what the course is like and see if that’s what you really want to do. Secondly, are these classes related to your major? You should definitely take these courses if they relate to your major because they will help you in the long run, you should also takes AP classes that you enjoy(however the ones related to your major is definitely worth the heavy coursework). Thirdly, are these classes that you want to take because your interested or because you want to “impress” colleges because the extra coursework to impress Colleges are not worth it(trust me I have prior experience) and if you don’t like the classes you may not due as well in them if you enjoyed the classes. Lastly, do you have time to manage all these classes? It is ok to say that your human and can not manage all these classes, if so pick and choose. Remember, it is better to have 2 AP classes and have A’s in them vs 4 with Bs and Cs with them. Regardless, what you choose you can always switch at the beginning of the other year and you can always take one of these AP classes later in your high school career! Have a good summer and good luck next year!