DIN 53804-1 Calculation of Cpk

Dear Q Colleges,
Does somebody have experience, using the norm DIN 53804-1 to calculate the Cpk.
My Situation is the following:
1. I need to calculate de Cpk in the pre-series to evaluate the process capability.
2. Because of short productions, I never get enough parts (values) to make the calculation.
As far as I know I can use the Norm DIN 538014-1 to calculate the Cpk using factor values of the t-Verteilung (Student Verteilung) and the level of reliability (Vertrauensniveau x-Faktoren).
If you have experience using these statistical norms, please contact me.
Kind Regards
Osman