Record average response time during practice round and embedd as timer value for subsequent blocks?

Hi Everyone,
Background:
I am trying to programm a semantic word association questionnaire, where people get a limited time to respond (e.g. 8 sec) per question where they have to type a word for each question.
I want to exert enough pressure that the entire task is limited and that they do nor result to internet search strategies or of the sort while they are filling in the questionnaire. However, I do not want to exert so much pressure that they have difficulties finishing the whole questionnaire.
The problem:
I would like to include a practice block where I time the average response duration (practice block duration/ question).
I would like to take the average response time variable and implement it as a display timer for all subsequent questions during the test block.
Solutions?
I am new to JAVA so help would be much appreciated!
Thank you in advance :)