Pumping Lemma length, $K$ for context-free language

Question

Please help me understand, and if possible, tips, to determine a pumping length $K$.

Suppose I have the example :

Let $G$ be a Context-Free-Grammar with a set of variables $\{S,A,B,T\}$, set of terminals $\{0,1\}$, start variable $S$, and rules:

$$\begin{align}S&\to ABA \mid SS\\ A&\to S0 \mid 1C1\\ B&\to S1 \mid 0\\ C&\to 0 \end{align} $$

Now given the above, how would I give a suitable pumping length $K$, and please explain how you actually got it from $K$.

Thank you, learning this would be of great help. This is NOT HOMEWORK.

Thanks.