At what point do you decide to jump into research? Before diving into "real research", there are some students who prefer to learn bare minimum prerequisite courses/material and then start off reading survey papers and develop their skills.

There are others who prefer to go through courses from Introduction to Advanced to Independent Study before finally diving in. 

The former would probably face problems of fundamentals while the latter spends too much time learning things which might not be completely useful.

At what point should one (Assume, if necessary, that I am talking about STEM) decide to dive into research while making sure that one is neither being too hasty nor slow?

Take for e.g. that a person wishes to code a software in Python which does engineering calculations. He would either read something like Intro to Python and then directly start coding or he could also read documentations of other Math libraries, similar libraries in C/Fortran, study coding efficiency and thumb rules and then start. 

How do you prevent yourself from taking up too little or too much time to begin?
As aeismail says, there's no single answer. As with most things in life, it's hard to know when you're "ready" to do something. The best way is to jump in when you feel like you don't need to prep any more, and then be prepared to shore up weaknesses as you spot them.  

Over time, you'll learn how to prepare yourself to embark on a new research topic: some people like to start solving a problem first, and then return to the literature when they get stuck. Some people like to read a few key papers to get a sense of the main open problems and techniques, and then go off and play. 

The only important thing is that you do something, and not just wait on the sidelines for a mythical feeling of "readiness" to emerge. Be fearless, like a 2 year old who doesn't know enough to be afraid :)